JP2006109374A - Electronic camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic camera capable of zooming and reproducing non-compressed image data at high speed. <P>SOLUTION: The electronic camera comprises: an imaging device; an A/D conversion part; an image processing part for generating image data comprised of M pieces of pixels in the main scanning direction × N pieces of pixels in the vertical scanning direction by applying image processing to the digital signal of the A/D conversion part and for applying image processing such as resolution change to the image data in the case of recording and reproducing; a memory for temporarily storing the image data; a recording part for storing the image data without compressing them; a data bus for interconnecting the image processing part, the memory and the recording part to transfer the image data or the like; and a transfer command part for performing DMA transfer of the image data to respective parts for the unit of a unit transfer data amount, partitioning the image data constituting one picture with tiles each comprised of (m) pieces of pixels in the main scanning direction × (n) pieces of pixels in the vertical scanning direction and for correlating the image data for the unit of the tile. In the electronic camera, the product of the number (m) of pixels in the main scanning direction of the tile and the number of bytes in the image data per pixel is set to the integer multiple of the unit transfer data amount. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electronic camera. In particular, the present invention relates to a memory arrangement technique for image data suitable for zoom-reproducing uncompressed image data at high speed, or for reducing and displaying an image having a size that cannot be batch processed by an image processing unit.

  During the imaging operation of the electronic camera, the subject image is photoelectrically converted by the image sensor and output as an analog signal, digitized by the A / D converter, and input to the image processor. The image processing unit performs processing such as black level adjustment, white balance adjustment, gamma correction, color interpolation, color conversion, and edge enhancement on the digital data. The image data subjected to these processes is once stored in a memory and then recorded on a memory card.

  In a general electronic camera, only a part of image processing such as black level adjustment is applied to a digital signal input from an A / D conversion unit, and then temporarily stored in a memory, and an image for one screen is stored in the memory. In many cases, the remaining image processing is performed by inputting the data again into the image processing unit when the data is ready. This is because (1) there are many image pickup devices that output an image signal divided into a plurality of fields, so that an image signal output by a skipped line cannot be subjected to processing such as interpolation. (2) AWB (Auto White Balance) This is because the adjustment value cannot be determined unless the image signal of the entire screen is analyzed in the adjustment, and it is difficult to directly perform the AWB adjustment on the image signal output from the image sensor.

Further, during the playback operation of the electronic camera, the image data of the memory card is read into the memory, subjected to processing such as resolution conversion by the image processing unit, and is played back on the monitor of the electronic camera.
Thus, the frequency of data transfer of image data in the electronic camera is high, and it is indispensable to optimize the structure of the image data for data transfer in order to speed up the image processing of the electronic camera. For this purpose, it is important to continuously store the image data in the storage area of the memory in the order in which the image processing unit processes.

  Here, an SDRAM having a large capacity and excellent cost is often used as a memory for temporarily storing image data in an electronic camera. In the case of inputting / outputting image data from / to the SDRAM, it is necessary to specify the address of the storage area of the memory (row address (Row Address), column address (Column Address)). If the image data is not sequentially arranged in sequence, the efficiency of data transfer decreases because random access is performed by designating the row address and the column address for each image data. However, if the image data is arranged sequentially in sequence, the top image data specifies the row address and the column address, but the next image data can be transferred simply by giving the incremented column address. As a result, the data transfer speed is significantly improved. This data transfer method is called a burst mode (Burst Read / Burst Write).

  The data transfer in the burst mode can use the burst mode of the SDRAM itself, but in that case, it is difficult to freely select the data amount (unit transfer data amount) of one burst transfer. . Any SDRAM controller capable of generating an incremented column address can realize burst transfer, and this method is more convenient because the unit transfer data amount can be freely selected. Usually, this burst mode is often used. The data transfer in the burst mode is efficiently transferred for each unit transfer data amount of the DMA transfer by DMA (Direct Memory Access) transfer by the DMA controller without using the CPU. In this case, the row address is designated only once at the beginning for each DMA transfer (burst mode).

  On the other hand, Exif (Exchangeable Image File Format for Digital Still Camera), which is a format standard for image data of an electronic camera, defines a JPEG format compression method and a TIFF format non-compression method. In general, in an electronic camera, a shot still image is often JPEG-compressed and recorded on a memory card. However, in an electronic camera especially for high-quality shooting, the image data of the shot image is in an uncompressed TIFF format. It is often stored (see Patent Document 1).

According to the above Exif standard, only the strip-type data structure is defined in the uncompressed TIFF format. Here, the strip method is a method of recording image data for one screen in association with each other in units of data blocks (strip) in which one or more lines are collected.
JP 7-274108 A

As described above, arranging image data at consecutive addresses in the memory is advantageous because data transfer in burst mode can be used. In this case, the image data is arranged at continuous addresses along the main scanning direction. However, it may be inconvenient if the image data is arranged at consecutive addresses at the line breaks. The following is an example.
FIG. 10 is a diagram illustrating a case where an image is zoom-displayed on the monitor of the electronic camera. In this case, the image data of one screen on the memory is read out only in a desired range, and the image is cut out. Then, the image data cut out by the image processing unit is subjected to resolution conversion and displayed on a monitor.

  Here, as shown in FIG. 11, two-dimensional addressing (for example, when one image is divided into blocks of a predetermined size, the address from the end of the block located in the middle of a certain line to the end of the block of the next line is performed. In a DMA controller that can perform DMA transfer without skipping), image cropping can be easily realized by DMA transfer, so that high-speed zoom processing is possible. When an image is cut out by DMA transfer as described above, it is indispensable to match the start position of each line of image data with the start address of DMA transfer.

  The number of pixels in the main scanning direction of the image data (the number of pixels in one line) is various, and there are various image data formats such as RGB4: 4: 4 and YCbCr4: 2: 2. The amount of data (number of bytes) for the line is also different. Therefore, in order to satisfy the above requirements for various image data, it is necessary to devise arrangement of the image data on the memory. That is, the image data is not arranged at continuous addresses at the line breaks, but the address of the image data of the next line is appropriately jumped according to the amount of image data of one line (see FIG. 12). Normally, image data is arranged in this way on the memory inside the camera.

  However, when strip-type image data in the TIFF format is arranged at continuous addresses in the memory, the amount of image data for one line matches the integer multiple of the amount of data for DMA transfer, and the DMA transfer start address and each line It is extremely rare for the head position of the to match. Therefore, when image data is DMA-transferred in the scanning order, the head data of the next line is often connected to the last data of the previous line and DMA-transferred, and the head position of each line varies (see FIG. 13). .

As described above, when strip-type image data is read from the memory card and the image data is zoom-reproduced, it is arranged on the memory inside the camera so as to be an address convenient for DMA transfer (see FIG. 12). Must be changed. Therefore, there is room for improvement in that the reproduction speed is significantly reduced.
In addition, dummy data is added to the end of each line in order to match the image data amount of one line with an integer multiple of the DMA transfer data amount and align the head position of each line in the DMA transfer. It is also possible to record. In this case, the dummy data to be added is based on the above address jump. However, in the strip format of the TIFF format, it is not permitted to insert dummy data between lines. Accordingly, it is necessary to delete dummy data from the image data on the memory during recording, and to insert dummy data when arranging the image data on the memory during reproduction. Since these operations are performed by CPU software processing, extra overhead time occurs during recording and reproduction.

  On the other hand, the TIFF format also allows recording of image data with a tiled data structure. This tile method is a method in which image data for one screen is recorded in association with a unit of a rectangular data block of an arbitrary size called a tile. The tile-type image data holds information on the number of main scanning direction pixels M and the number N of sub-scanning directions and the number of main scanning direction pixels m and the number of sub-scanning direction pixels n of one screen in a tag.

  In this tile type data structure, dummy data may have to be added to the end of the screen in the main scanning direction in order to make the tile size constant. However, even when such dummy data is added, the data size of the dummy data can be detected from the information of the size of one screen and the tile size. Therefore, this dummy data can be easily discarded during image reproduction. In TIFF, it is recognized that dummy data is added to the end of the image data of one screen in the main scanning direction (line) and recorded in a tile structure. Therefore, the tile method may avoid the above-described problems.

However, even in this tile method, when the data amount of the tile in the main scanning direction is not an integral multiple of the unit transfer data amount of the DMA transfer, the head position of each line varies in each tile. Therefore, there is still room for improvement in that the same problem as in the case of the strip method described above can occur.
The present invention has been made to solve the above-described problems of the prior art, and an object thereof is to provide an electronic camera that can zoom-reproduce uncompressed image data at high speed.

  According to the first aspect of the present invention, an image sensor that photoelectrically converts a subject image, an A / D converter that digitizes an output signal of the image sensor, and a digital signal of the A / D converter are subjected to image processing. An image processing unit that generates image data composed of M pixels in the main scanning direction × N pixels in the sub-scanning direction, performs image processing such as resolution conversion on the image data during recording and reproduction, and temporarily stores the image data A memory, a recording unit that stores the image data in an uncompressed manner, a data bus that interconnects the image processing unit, the memory, and the recording unit to transfer the image data, and unit transfer of the image data DMA transfer is performed to each unit for each data amount, and the image data constituting the one screen is divided into tiles each composed of m pixels in the main scanning direction × n pixels in the sub scanning direction, and the image data is divided into tiles. An electronic camera including a transfer command unit to be associated, wherein a product of the number m of pixels in the main scanning direction of the tile and the number of bytes of the image data per pixel is set to an integral multiple of the unit transfer data amount. It is characterized by.

  According to a second aspect of the present invention, in the first aspect of the invention, the image processing unit is a first dummy having a data amount corresponding to a difference between an integral multiple of the unit transfer data amount and a data amount in the main scanning direction of one screen. Data is added to the end of the main screen in the main screen in the one screen, and the transfer command unit transfers the second dummy data having an integer multiple of the unit transfer data amount by the DMA transfer in the main screen in the main screen direction. The amount of data in the main scanning direction of the image data of one screen is an integral multiple of the amount of data in the main scanning direction of the tile by adding at least one of the first dummy data or the second dummy data. To match. In the present invention, after the dummy data is added, one screen is divided into tiles and stored in the recording unit.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the number of tiles in the main scanning direction of the one screen is one, and the image data is partitioned by the tiles only in the sub-scanning direction. It is characterized by being.
According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the number of tiles in the one screen is one, and the image data is included in one tile.

  According to a fifth aspect of the present invention, in the first or second aspect of the present invention, the image processing unit further includes a determination unit that determines whether the image data of the one screen can be processed in a lump. When the determination result can be processed, the transfer command unit sets the number of tiles in the main scanning direction of the one screen to one or a plurality, and the determination result of the determination unit cannot be processed. The transfer command unit sets the number of tiles in the main scanning direction of the one screen to one.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the data bus width of the data bus is 16 bits or 32 bits, and the unit transfer data amount is equal to the data bus width. The amount of data is obtained by multiplying by a power of 2.
According to a seventh aspect of the present invention, in the invention according to any one of the first to sixth aspects, the detection means further detects the number of tiles in the main scanning direction of the image data recorded in the recording unit, and the detection is performed. When the number of tiles in the main scanning direction detected by the means is plural, the transfer command unit scans the image data recorded in association with the recording unit in units of tiles in the main scanning of the one screen at the time of reading by DMA transfer. It rearranges in order of scanning for every direction line, It is characterized by the above-mentioned.

  According to an eighth aspect of the present invention, in the seventh aspect of the invention, the detection means for detecting the number m of pixels in the main scanning direction of the tile recorded in the recording unit and the number of bytes of the image data per pixel, and the recording In the case of transferring the image data read from the unit to the memory to the image processing unit, the number m of pixels in the main scanning direction of the tile detected by the detection unit and the number of bytes of the image data per pixel are detected. The apparatus further comprises transfer data amount changing means for changing the unit transfer data amount under a condition that the unit transfer data amount is a ratio of 1 / integer to the product.

According to a ninth aspect of the present invention, in the invention according to any one of the first to eighth aspects, the image data includes 8 bits of RGB 4: 4: 4 data, 8 bits of YCbCr 4: 4: 4 data, and 8 bits of each. The data format is any one of YCbCr4: 2: 2 data of bits, and three components of the data format are alternately arranged in color order.
According to a tenth aspect of the present invention, in any one of the first to ninth aspects, the image data is uncompressed and stored in the recording unit in a TIFF format.

  In the present invention, image data arranged in the scanning order of the image sensor on the memory of the camera by a DMA controller capable of two-dimensional addressing, and data arrangement associated with tile units by DMA transfer at the time of recording on a recording medium Can be sorted. Further, when reproducing image data, the image data of the recording medium arranged in association with the tile unit can be rearranged by DMA transfer into the data array in the scanning order of the image sensor.

  The image data read from the recording medium to the memory at the time of reproduction is in a state where the head position of each line is aligned with the head address of DMA transfer. Accordingly, even when zoomed playback of uncompressed image data is performed, an image can be cut out by DMA transfer, and unnecessary overhead time due to processing such as rearrangement of image data can be eliminated. In addition, even when an image that has a large image size and cannot be batch-processed is displayed in a reduced size, a high-speed reduced display process can be realized by cutting the image by DMA transfer, dividing the image, and performing the reduction process.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.
(Description of the first embodiment)
FIG. 1 is a schematic diagram of an electronic camera 100 according to a first embodiment of the present invention (corresponding to claims 1 to 9). The electronic camera 100 according to the first embodiment includes a photographing lens 1, a lens driving unit 2 that drives the photographing lens 1, an imaging device 3, a timing generator (TG) 4 that generates a driving pulse of the imaging device 3, and the like. A / D conversion unit 5, image processing unit 6, SDRAM (memory) 7 and SDRAM controller 7a, DMA controller (transfer command unit) 8, monitor 9 and display controller 10 for displaying captured image data A picture bus 11, a system bus 12, a bus interface 13, a card interface 14, a recording medium (recording unit) 15, and a CPU 16.

  In the electronic camera 100 according to the first embodiment, image data (see FIG. 2) arranged on the SDRAM 7 in the scanning order of the image sensor 3 is DMA-transferred to a data arrangement associated with a tile unit when recording on the recording medium 15. When the image data is rearranged and the image data is reproduced, the image data on the recording medium 15 arranged in association with the tile unit is rearranged into the data array in the scanning order of the image sensor 3 by DMA transfer. Here, the tile is a rectangular image block having an arbitrary size (m × n). In the first embodiment, image data for one screen (M × N) is associated in units of tiles, and is uncompressed and recorded on the recording medium 15 in the TIFF format.

  Here, the data structure of the TIFF format tile system is shown in FIG. A file in the TIFF format includes a TIFF header, a directory part (IFD: Image File Directory), and an image data part associated with each tile. The TIFF header is arranged at the head of the file and is composed of data such as a TIFF file expression format and a pointer to the directory part.

  The directory portion is composed of the number information (β) of directory entries written in the directory portion, β directory entries, an offset to the next directory, and the like. Each directory entry contains a tag. As a tag of the directory entry, the number of pixels M (ImageWidth) in the main scanning direction of one screen, the number N of pixels in the sub scanning direction of one screen (ImageLength), the number of pixels m in the main scanning direction of the tile (TileWidth), and the sub scanning direction of the tile There are types such as the number of pixels n (TileLength), the offset of each tile (TileOffsets), and the number of bytes of each tile (TileByteCounts). In the tile data structure, dummy data may need to be added to the end of the screen in the main scanning direction in order to make the tile size constant. The data size of data can be detected.

(Image sensor, A / D converter)
The image sensor 3 is disposed on the image space side of the photographing lens 1. On the light receiving surface of the image pickup element 3, light receiving elements that generate an analog image signal by photoelectrically converting a subject image are two-dimensionally arranged. The arrangement of the light receiving elements of the image pickup element 3 covers an area larger than the number of pixels of image data of one screen (M in the main scanning direction and N in the sub scanning direction). The image signal of the area outside the number of pixels of one screen is used for interpolation of the peripheral portion of the image of one screen. The output of the image sensor 3 is converted into a digital image signal (original image data: Raw Image Data) by the A / D conversion unit 5 and input to the image processing unit 6.

(Image processing unit)
The image processing unit 6 performs image processing (processing such as defect correction, gamma correction, interpolation, color conversion, and edge enhancement) on input image data. Although not particularly limited, the image data generated by the image processing unit 6 includes 8-bit RGB 4: 4: 4 data, 8-bit YCbCr 4: 4: 4 data, and 8-bit YCbCr 4: 2: It is standard to use one of two data formats. Further, it is preferable that the three components of the data format described above have three color signals alternately arranged in color order. This is for simplifying the circuit configuration of the electronic camera 100 by simplifying the addressing at the time of data transfer.

  Further, the image processing unit 6 has a buffer memory corresponding to a unit transfer data amount described later of the DMA controller 8. When the amount of output image data at the end of the line is less than the buffer memory capacity (that is, when the amount of image data for one line is not an integral multiple of the unit transfer data amount), the image processing unit 6 Dummy data (first dummy data) corresponding to the shortage of (unit transfer data amount) is added to the end of the image data and output.

(SDRAM, SDRAM controller)
Image data is temporarily stored in the SDRAM 7. When image data is temporarily stored in the SDRAM 7, (1) only a part of image processing is performed in the image processing unit 6, and the image data output in the scanning order of the image sensor is temporarily saved until one screen is prepared. (2) When the image data for one screen on which the image processing by the image processing unit 6 has been completed is temporarily saved before being recorded on the recording medium 15. The SDRAM controller 7a serves to output a row address, a column address, and a read signal or a write signal to the SDRAM 7 according to an address generated by the DMA controller 8 and a signal indicating the transfer direction.

(DMA controller)
The DMA controller 8 executes DMA transfer of image data for each unit transfer data amount. The DMA controller 8 determines an image data transfer direction in response to an instruction from the CPU 16 and generates an address.
The DMA controller 8 supports a burst mode (Burst Read / Burst Write) in which data of a predetermined length is collectively transferred continuously by one DMA transfer. During the burst transfer, the SDRAM controller 7a receives the address generated by the DMA controller 8 and increments the column address.

Here, when the image data is DMA-transferred in the burst mode, it is preferable to transfer the data amount of the data bus width for every power of 2 and perform the transfer once. In this case, the unit transfer data amount is a data amount obtained by multiplying the data amount of the data bus width by a power of 2.
Since the page size (number of column addresses) of SDRAM is generally a power of two, if the unit transfer data amount is set to the above value, one burst mode DMA transfer can be terminated at the SDRAM page boundary. . When the SDRAM page changes, the row address (Row Address) must be changed. However, in the above case, one burst mode DMA transfer ends at the SDRAM page boundary, and only one row address specification is required. Transfer speed is significantly improved. However, the start address of the DMA transfer needs to be aligned with the start of the SDRAM page.

  There are eight types of DMA transfer of image data in the first embodiment. The first is a case where image data that has undergone some image processing by the image processing unit 6 is transferred to the SDRAM 7 in accordance with the scanning order of the image sensor. The second case is a case where image data for one screen temporarily saved in the SDRAM 7 is transferred to the image processing unit 6. The third is a case where image data for one screen image-processed by the image processing unit 6 is transferred to the SDRAM 7. The fourth case is a case where the image data of the SDRAM 7 is transferred to the recording medium 15 in association with the tile unit. The DMA transfer so far is performed in a series of imaging operations of the electronic camera 100.

  In the fifth case, uncompressed image data in the TIFF format stored in the recording medium 15 is transferred to the SDRAM 7. The sixth is a case where uncompressed image data stored in the SDRAM 7 is transferred to the image processing unit 6. The seventh case is a case where image data subjected to image processing such as resolution conversion in the image processing unit 6 is transferred to the SDRAM 7. The eighth is a case where image data of the SDRAM 7 on which image processing has been performed is transferred to the display controller 10. These DMA transfers are performed when image data after imaging is read into the electronic camera 100 and reproduced.

  Here, the DMA controller 8 of the first embodiment performs two-dimensional addressing (for example, when one image is divided into blocks of a predetermined size, the block of the next line from the end of the block located in the middle of a certain line). DMA transfer can be performed by skipping the address at the tip. The DMA controller 8 according to the first embodiment assigns dummy data and rearranges image data using the above two-dimensional addressing.

  First, at the time of the third DMA transfer, if the data amount of one line of image data does not coincide with an integer multiple of the data amount of the tile in the main scanning direction, the DMA controller 8 determines the end of one line according to the instruction of the CPU 16. Is written in the SDRAM 7, the address of the image data at the head of the next line is jumped. At this time, the image data including the end of one line written in the SDRAM 7 may be given the first dummy data by the image processing unit 6. By this address jump, dummy data (second dummy data) having a data amount integral multiple of the unit transfer data amount is given to the end of one line in the main scanning direction (see FIG. 5).

  Further, at the time of the fourth DMA transfer, the DMA controller 8 rearranges the image data for one screen arranged on the SDRAM 7 according to the scanning order of the imaging elements in association with each other in tile units. At this time, dummy data (first dummy data and second dummy data) corresponding to the number m of pixels in the main scanning direction of the tile is given to the end of one screen in the main scanning direction (line). The amount of data in the main scanning direction matches the integer multiple of the amount of data in the main scanning direction of the tile.

Similarly, at the time of the fifth DMA transfer, the DMA controller 8 rearranges the image data associated and recorded in tile units in the scanning order. When one screen is partitioned by a plurality of tiles, the size of each tile is set to the same size.
(Picture bus, system bus)
An image processing unit 6 and a display controller 10 are connected to the picture bus 11. The system bus 12 includes a lens driving unit 2, a timing generator 4, an image processing unit 6, an SDRAM 7 and an SDRAM controller 7, a DMA controller 8, a display controller 10, a card interface 14, and a CPU 16. It is connected. The picture bus 11 and the system bus 12 are connected to the SDRAM 7 via the bus interface 13. Although not particularly limited, the data bus width of the picture bus 11 and the system bus 12 is typically 16 bits or 32 bits.

(Card interface, recording medium)
A recording medium 15 is detachably attached to the card interface 14. The card interface 14 incorporates a buffer memory corresponding to the above-described burst mode DMA transfer, and can read / write data from / to the recording medium 15 in the burst mode. Further, the TIFF format tile-type image data is finally stored in the recording medium 15. The recording medium 15 corresponds to a known semiconductor memory such as CompactFlash (registered trademark).

(CPU)
The CPU 16 controls the operation of each unit of the electronic camera 100 via the system bus 12 and executes arithmetic processing necessary for focusing control and exposure control of the electronic camera 100. In particular, in the first embodiment, the CPU 16 has the following functions.
First, the CPU 16 has a function of setting the number of tiles and the arrangement of tiles in one screen and the size (m × n) of one tile. Here, the size of one tile in the main scanning direction is set under the condition that the product of the number m of pixels in the main scanning direction of the tile and the number of bytes of image data per pixel is an integral multiple of the unit transfer data amount of DMA transfer. (See FIG. 3). This is because the data arrangement according to the scanning order of the image sensor 3 and the tile data arrangement can be rearranged by DMA transfer by aligning the head position of each line in the tile with the DMA transfer head address. It is for doing so.

  Note that the layout of tiles for one screen may be such that, for example, the number of tiles in the main scanning direction of one screen is set to one, and the image data is partitioned by tiles only in the sub-scanning direction (see FIG. 6 (a)). Alternatively, similarly to the example of FIG. 12, only one tile may be arranged on one screen so that the image data of one screen is included in one tile (see FIG. 6B).

At this time, if the number of pixels M in the main scanning direction of one screen does not match an integer multiple of the number of pixels m in the main scanning direction of the tile, dummy data is added to the end of the main scanning direction of one screen and the amount of data May be adjusted (see FIG. 2). The dummy data is given by the image processing unit 6 and an address jump by the DMA controller 8.
Second, the CPU 16 instructs the DMA controller 8 to rearrange the image data by jumping the address during DMA transfer. Specifically, in the fourth DMA transfer (when writing image data from the memory to the recording medium), the image data arranged in the scanning order for each line is associated with the DMA controller 8 in tile units. And give instructions to sort. In the fifth DMA transfer (when reading image data from the recording medium to the memory), the image data stored in association with the recording medium 15 in units of tiles is stored for each line with respect to the DMA controller 8. An instruction to rearrange them in the scanning order is given.

Third, the CPU 16 has a function of changing the unit transfer data amount in accordance with the image data in the sixth DMA transfer (when image data on the SDRAM 7 is transferred to the image processing unit 6). This is to enable zoom reproduction by cutting out image data even when reproducing image data recorded by another electronic camera having a different unit transfer data amount.
Specifically, the CPU 16 detects the number m of pixels in the main scanning direction of the tile and the number of bytes of the image data per pixel from the TIFF header portion and the directory portion tag of the image data. Then, the CPU 16 executes the DMA under the condition that the ratio is 1 / integer to the product of the number m of pixels in the main scanning direction of the tile and the number of bytes of image data per pixel (data amount in the main scanning direction of the tile). The setting of the unit transfer data amount of the controller 8 is changed.

(Operation of the first embodiment)
The electronic camera 100 of the first embodiment is configured as described above, and hereinafter, the operation will be described separately for an imaging mode and a playback mode.
(In shooting mode)
FIG. 7 is a flowchart of shooting modes in the electronic camera 100 of the first embodiment.

  When the electronic camera 100 is in the shooting mode, first, the CPU 16 determines an exposure condition and the like by a user operation. Thereafter, according to the shutter release of the user, the image sensor 3 is controlled according to the exposure condition to execute photoelectric conversion of the subject image (S1). The image signal for one screen of the image sensor 3 is read out in a plurality of fields by means of, for example, outputting odd lines and even lines separately to two fields. The output image signal is digitized by the A / D conversion unit 5 to become original image data, and is output to the image processing unit 6 in the order of input (S2).

  The image processing unit 6 performs only partial image processing such as defective pixel correction and black level adjustment on the input original image data (S3). In the above case, since the image signal of each field is output with a skipped line, the image signal is not subjected to processing such as interpolation, and in the AWB adjustment, the adjustment value is determined unless the image signal of the entire screen is analyzed. This is because there is not. Then, the DMA controller 8 DMA-transfers the image data to the SDRAM 7 via the picture bus 11 according to the writing instruction of the CPU 16 (S4).

The CPU 16 sets the size (m × n) of one tile (S5). The size of one tile in the main scanning direction is set under the condition that the product of the number of pixels m in the main scanning direction of the tile and the number of bytes of image data per pixel is an integral multiple of the unit transfer data amount of DMA transfer. .
At this time, the tile size is determined by the CPU 16 in consideration of various conditions such as whether or not the image processing unit 6 can process the image data of one screen at a time. For example, when the image processing unit 6 cannot process the image data at the time of reproduction, it is necessary to divide the image into a plurality of parts in the horizontal direction and perform a reduction process for each of the divided strip-like small images. In this case, since it is necessary to cut out the images so that the boundary portions of the divided images overlap, it is necessary to set the number of tiles in the main scanning direction of one screen to one. On the other hand, when the image processing unit 6 can collectively process image data of one screen, the number of tiles in the main scanning direction of one screen may be set to one, or may be divided into a plurality of tiles.

The CPU 16 instructs the DMA controller 8 to transfer the image data to the image processing unit 6 when the image data for one screen including a plurality of fields is stored in the SDRAM 7. The original image data is read from the SDRAM 7 via the picture bus to the image processing unit 6 by DMA transfer (S6).
The image processing unit 6 executes remaining signal processing such as white balance adjustment, gamma correction, and color interpolation on the image data (S7). At this time, if the image data amount at the end of the line is less than the buffer memory capacity, the image processing unit 6 sets the first dummy data corresponding to the shortage of the buffer memory capacity (unit transfer data amount) at the end of the image data. Give. Accordingly, the image data for one line output from the image processing unit 6 always has a data amount that is an integral multiple of the unit transfer data amount, and can be DMA transferred.

Further, the CPU 16 determines whether or not the data amount in the main scanning direction of one screen matches an integer multiple of the data amount in the main scanning direction of the tile (S8). If they match (YES side), the DMA controller 8 writes the image data for one screen output from the image processing unit 6 into the SDRAM 7 in accordance with the scanning order of the image sensor (S9).
On the other hand, if they do not match (NO side), the DMA controller 8 writes the image data for one screen output from the image processing unit 6 into the SDRAM 7 while adding dummy data by jumping addresses ( S10). The DMA controller 8 jumps the address of the image data at the head of the next line when the image data including the end of one line is written into the SDRAM 7. By this address jump, second dummy data having a data amount that is an integral multiple of the unit transfer data amount is given to the end of one line in the main scanning direction (see FIG. 5).

  The CPU 16 generates a TIFF header part and a directory part, and writes them in a storage area (located at the top part of the image data) reserved in advance in the SDRAM 7 (S11). Here, if the data amount of the TIFF header portion and the directory portion does not match the integral multiple of the unit transfer data amount of the DMA transfer, the start position of the subsequent image data portion is shifted from the start address of the DMA transfer. . Therefore, in this case, the CPU 16 adds dummy data to the end of the data in the TIFF header part or the directory part, and adjusts so that the head position of the image data part matches the head address of the DMA transfer.

  Then, the DMA controller 8 jumps the address according to the tile size set in step S7, rearranges the image data arranged in the scanning order on the SDRAM 7 into the data arrangement associated with the tile unit by the DMA transfer, and the recording medium 15 (S12). The image data stored for each tile in the recording medium 15 is stored in a state where the head position of each line is positioned at the head address of DMA transfer. A series of imaging operations is completed through the above steps.

(In playback mode)
FIG. 8 is a flowchart of the playback mode in the electronic camera 100 of the first embodiment.
First, the CPU 16 reads the TIFF header part and directory part of the image data in the recording medium 15 (S21). Then, the CPU 16 detects the number m of pixels in the main scanning direction of the tile, the number of bytes of image data per pixel, and information on the start position (offset) of each tile (S22).

Next, the CPU 16 has a unit transfer data amount that is 1 / integer of the product of the number m of pixels in the main scanning direction of the tile and the number of bytes of image data per pixel (data amount in the main scanning direction of the tile). It is determined whether the ratio is reached (S23). If the determination result is YES, the process proceeds directly to step S25.
On the other hand, when the determination result is NO, the CPU 16 calculates an integral number with respect to the product of the number of pixels m in the main scanning direction of the tile and the number of bytes of image data per pixel (data amount in the main scanning direction of the tile). The setting of the unit transfer data amount of the DMA controller 8 is changed under the condition of the ratio of 1 (S24).

  The DMA controller 8 DMA-transfers the image data for one screen stored in the recording medium 15 to the SDRAM 7 and reads it in accordance with the reading instruction of the CPU 16. At this time, the DMA controller 8 rearranges the data arrangement of the image data associated with each tile and stored in the recording medium 15 according to the instruction of the CPU 16 in the order of scanning of one screen by DMA transfer (S25). The image data on the SDRAM 7 is in a state where the head position of each line is aligned with the head address of the DMA transfer.

The CPU 16 performs a process of excluding dummy data from the image data on the SDRAM 7 based on the effective pixel area data (M × N) of one screen and the tile size data (m × n) (S26).
The DMA controller 8 transfers the image data to the image processing unit 6 according to the reading instruction of the CPU 16 (S27). At this time, since the head positions of the respective lines are aligned, it is possible to easily cut an image into an arbitrary size by DMA transfer.

The image processing unit 6 performs processing such as resolution conversion on the image data cut out from the image data of one image (S28). The DMA controller 8 temporarily transfers the image data subjected to image processing such as resolution conversion to the SDRAM 7 according to the writing instruction of the CPU 16 (S29). Thereafter, the DMA controller 8 transfers the image data to the display controller 10 according to the read instruction of the CPU 16, and the image data is displayed on the monitor 9 (S30). A series of reproduction operations is completed through the above steps.
(Effect of 1st Embodiment)
In the electronic camera of the first embodiment, the data arrangement in the scanning order of the image sensor and the data arrangement associated with the tile unit are freely rearranged by DMA transfer by the DMA controller capable of two-dimensional addressing. Is possible. The image data read to the memory at the time of reproduction is in a state where the head position of each line is aligned with the head address of DMA transfer. Therefore, it is possible to cut out an image by DMA transfer.

  For example, when zooming out image data or when displaying an image whose image size is large and cannot be batch processed, a part of the image needs to be cut out and processed. In the first embodiment, the arrangement of the image data read to the SDRAM by DMA transfer at the time of reproduction is the data arrangement in the scanning order of the image sensor, and all the image cutout positions are aligned. Therefore, since the image can be cut out by DMA transfer, the image processing can be speeded up.

  Furthermore, in the electronic camera of the first embodiment, when dummy data is added to the end of one screen in the main scanning direction, the number of pixels M in the main scanning direction of one screen cannot be divided by the number of pixels m in the main scanning direction of the tile. However, the data arrangement can be rearranged by the DMA transfer, and the above effect can be obtained. It should be noted that the size of the dummy data given to one screen can be easily determined from the tag data in the directory part, and the dummy data exclusion process during reproduction is easy.

Furthermore, in the electronic camera of the first embodiment, the unit transfer data amount can be changed according to the image data. Therefore, when reproducing image data with another electronic camera, even if the unit transfer data amount differs between electronic cameras, the start position of each line can be matched with the start address of the DMA transfer, and the above-described effect is obtained. be able to.
(Supplementary items of the embodiment)
As mentioned above, although this invention has been demonstrated by said embodiment, the technical scope of this invention is not limited to the said embodiment. For example, in the playback mode of the above embodiment, it is assumed that image data of one screen is read out to SDRAM. However, only tiles including image data necessary for clipping are partially read out and transferred to the tiles by DMA transfer. The included image data may be rearranged in the scanning order.

  Furthermore, in the above-described embodiment, an example in which dummy data is added to the end of the main scanning direction of the screen is shown, but dummy data may be added to the end of the sub scanning direction of the screen according to the size of the tile. As an example, when the number N of pixels in the sub-scanning direction of the screen is an odd number and the number of pixels n in the main scanning direction of the tile is an even number, the effective pixel area (M × N) of one screen matches the area where the tiles are arranged. In other words, an extra line is generated at the end of one screen in the sub-scanning direction. In this case, the number of pixels of the difference is obtained from the number of pixels n in the sub-scanning direction of the tile and the remaining number of pixels, and a dummy data line corresponding to the number of pixels of the difference is given to the end of the sub-scanning direction of one screen ( (See FIG. 9).

  In an electronic camera compatible with the tile format of the TIFF format, it is particularly suitable when an image is zoomed at a high speed or when an image having a size that cannot be batch processed by the image processing unit is reduced.

It is a schematic diagram of the electronic camera of 1st Embodiment. It is a figure which shows the correspondence of the image data arrangement | positioning on SDRAM, and a tile. It is a figure which shows the size of the tile of FIG. It is a figure which shows the data structure of the tile system of a TIFF format. It is a figure which shows provision of the dummy data by the jump of the address of DMA transfer. It is a figure which shows the example of arrangement | positioning of the tile in 1st Embodiment. It is a flowchart of the imaging | photography mode in the electronic camera of 1st Embodiment. 3 is a flowchart of a playback mode in the electronic camera of the first embodiment. It is a figure which shows the example which provided the dummy data to the subscanning direction terminal of 1 screen. It is a figure which shows a mode that 1 screen is cut out in a block shape at the time of zoom reproduction. It is a figure for demonstrating the two-dimensional addressing by a DMA controller. It is a figure which shows arrangement | positioning of the image data on SDRAM. In the strip format of the TIFF format, it is a diagram showing a state in which the leading data of the next line is connected to the last data of the previous line and DMA transfer is performed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shooting lens 2 Lens drive part 3 Image pick-up element 4 Timing generator (TG)
5 A / D converter 6 Image processor 7 Memory 8 DMA controller 9 Monitor 10 Display controller 11 Picture bus 12 System bus 13 Bus interface 14 Card interface 15 Recording medium 16 CPU
100 electronic camera

Claims (10)

An image sensor that photoelectrically converts a subject image, an A / D converter that digitizes an output signal of the image sensor, and M digital signals in the main scanning direction by performing image processing on the digital signals of the A / D converter An image processing unit that generates image data including N pixels in the scanning direction and performs image processing such as resolution conversion on the image data during recording and reproduction; a memory that temporarily stores the image data; and the image data A non-compressed recording unit, a data bus that interconnects the image processing unit, the memory, and the recording unit to transfer the image data, and the like. A transfer instruction for transferring the image data constituting the screen and dividing the image data into tiles each including m pixels in the main scanning direction × n pixels in the sub-scanning direction, and associating the image data with the tile unit. An electronic camera equipped with a headquarters,
An electronic camera, wherein a product of the number m of pixels in the main scanning direction of the tile and the number of bytes of the image data per pixel is set to an integral multiple of the unit transfer data amount. The image processing unit adds first dummy data having a data amount corresponding to a difference between an integral multiple of the unit transfer data amount and a data amount of one screen in the main scanning direction to the end of the one screen in the main scanning direction. ,
The transfer command unit, by the DMA transfer, gives second dummy data having a data amount that is an integral multiple of the unit transfer data amount to the end in the main scanning direction of the one screen,
The amount of data in the main scanning direction of the image data of the one screen coincides with an integral multiple of the amount of data in the main scanning direction of the tile by adding at least one of the first dummy data or the second dummy data. The electronic camera according to claim 1, wherein   3. The electron according to claim 1, wherein the number of tiles in the main scanning direction of the one screen is one, and the image data is partitioned by the tiles only in the sub-scanning direction. camera.   The electronic camera according to claim 1, wherein the number of tiles in the one screen is one and the image data is included in one tile. A determination means for determining whether the image processing unit can collectively process the image data of the one screen;
When the determination result of the determination means can be processed, the transfer command unit sets the number of tiles in the main scanning direction of the one screen to one or more, and the determination result of the determination means is not processed. 3. The electronic camera according to claim 1, wherein, when possible, the transfer instruction unit sets the number of tiles in the main scanning direction of the one screen to one. 4.   The data bus width of the data bus is 16 bits or 32 bits, and the unit transfer data amount is a data amount obtained by multiplying the data bus width by a power of two. 6. The electronic camera according to any one of 5 above. The detection means further detects the number of tiles in the main scanning direction of the image data recorded in the recording unit,
In the case where the number of tiles in the main scanning direction detected by the detection unit is plural, the transfer command unit transfers the image data recorded in association with the recording unit in units of tiles on the one screen at the time of reading by DMA transfer. The electronic camera according to claim 1, wherein the electronic cameras are rearranged in the scanning order for each main scanning direction line. Detecting means for detecting the number m of pixels of the tile recorded in the recording unit in the main scanning direction and the number of bytes of the image data per pixel;
When transferring the image data read from the recording unit to the memory to the image processing unit, the number m of pixels in the main scanning direction of the tile detected by the detection unit and the byte of the image data per pixel Transfer data amount changing means for changing the unit transfer data amount under the condition that the unit transfer data amount is a ratio of an integer to the product of a number;
The electronic camera according to claim 7, further comprising:   The image data is any one of 8-bit RGB4: 4: 4 data, 8-bit YCbCr4: 4: 4 data, and 8-bit YCbCr4: 2: 2 data. The electronic camera according to any one of claims 1 to 8, wherein the three components are alternately arranged in a color sequence.   The electronic camera according to claim 1, wherein the image data is stored in the recording unit in a non-compressed format in a TIFF format.

Images