JP2005176140A - Image processing method and image processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing method and image processor in which a one-dimensional look up table (1DLUT) is created for each image to be stored in a memory having small capacity and converting process is performed at high speed. <P>SOLUTION: The 1DLUT that is created by sampling R, G, B of input image data for predetermined counts, and the input image data are stored from a RAM 6 to a predetermined memory area of a RAM 15 (step 52). While referring to the 1DLUT stored in the RAM 15, color correction is performed using an interpolation formula upon the R, G, B data for each pixel of the input image stored in the RAM 15 (step 53). Color-corrected output image data are stored from the RAM 15 to the RAM 6 (step 54) and of all the pixels of the image of an inputted frame are corrected, color correcting process is performed upon the next frame and if no correction is performed, processing is returned to the step 52 (step 55). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image processing method and an image processing apparatus, and more specifically, an image processing method and image processing for converting an input image according to a 1DLUT (one-dimensional lookup table) created for each input image. It relates to the device.

  Conventionally, as a method of performing data conversion at high speed, a method using an LUT (Look Up Table) is known. Data conversion by LUT is, for example, conversion of image brightness, contrast, hue, etc. (R (red), G (green), B (blue) to Y (yellow), M (magenta), C (cyan)). In this case, the pixel value of the image before conversion is input as an index (address) to the LUT, and the stored value corresponding to the index is converted into the converted value after conversion. Are output as pixel values. The stored value is fixed for each input device.

  In image processing, a configuration aimed at providing a method for correcting an image of a certain input device to an image that approaches gradation reproduction and color reproduction realized by a silver halide film, paying attention to preferable color reproduction It has been known. (For example, Patent Document 1) This Patent Document 1 holds a profile of an input device and a profile of an output target film, and color reproducibility of input image data based on the profile of the input device and the profile of the output target film. A table for making the color near the color reproducibility of the output target film is created, and a configuration for performing color correction on input image data using the created table is disclosed.

JP 2000-050097 A

However, since a large amount of data is generally registered in the LUT, a large capacity memory is required as a memory for storing the data. For example, the image (input image) captured by the scanner reproduces the color by additive color mixture that changes the emission luminance of each of the phosphors of three colors R, G, and B for each pixel. 1DLUT (one-dimensional lookup table) for each of the R, G, and B channels is created with 14 bits of color information per pixel and 16 bits of color information per pixel of the output image after conversion. The amount of information held is 2 ¹⁴ × 16 × 3 = 786432 bits, that is, 96 Kbytes. For this reason, a 96 Kbyte memory and an access gate are required. The data conversion time by 1DLUT is only the memory access time. However, when the capacity of 1DLUT is increased, the 1DLUT cannot be stored in the memory (internal memory) in the device that performs processing. There is no choice but to store 1DLUT. In this case, compared to the internal memory, it takes time to access the external memory, and accordingly, each process such as conversion processing takes time.

  Further, if an LUT is created for each input image in order to make the output image high quality, a memory area several times the information amount of the input image is required with respect to the memory capacity described above. Therefore, a large-capacity memory is required, leading to an increase in cost.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide an image processing method and an image processing method in which a 1DLUT is created for each image so as to be stored in a memory having a small capacity, and conversion processing is performed at high speed It is to provide a processing apparatus.

  In order to achieve such an object, an image processing method of the present invention generates an image data acquisition step, and creates a one-dimensional lookup table (1DLUT) at sampling points at a predetermined interval based on the image data. A creation step, a storage step of storing the 1DLUT in an internal memory of a conversion processing unit that performs conversion processing using the 1DLUT, and output data output from the 1DLUT based on the image data by the conversion processing unit A conversion process step of converting the image data by performing an interpolation process.

  The image processing apparatus of the present invention includes an acquisition unit that acquires image data, a generation unit that generates a one-dimensional lookup table (1DLUT) at sampling points at predetermined intervals based on the image data, and the 1DLUT. Conversion processing means for performing conversion processing using the 1DLUT, an internal memory included in the conversion processing means for storing the 1DLUT, and output data output from the 1DLUT based on the image data by the conversion processing means Conversion processing means for converting the image data by performing interpolation processing on the image data.

  The “conversion processing means” of the present invention can be a DSP (digital signal processor).

  As described above, according to the present invention, based on the acquired image data, a one-dimensional lookup table (1DLUT) is created at sampling points at a predetermined interval, and the 1DLUT is stored in the internal memory of the conversion processing means. Thus, the conversion processing means performs an interpolation process on the output data output from the 1DLUT based on the image data to convert the image data, so that the 1DLUT can be stored in the internal memory of the image processing means having a small capacity. Each time it is created, the conversion process can be performed at high speed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration including peripheral devices of a film scanner which is an image processing apparatus according to an embodiment of the present invention.

  In FIG. 1, a CPU 1 executes control processing of the operation of the film scanner, data processing, and the like. The ROM 3 is preset with programs relating to each control of the film scanner, including programs shown in FIGS. 6 and 7 described later. The CPU 1 controls the film scanner by executing a program stored in the ROM 3. The controller 5 controls a DSP (digital signal processor) 7 that performs various processes such as color correction, a CCD 8 that is an image input device, and a machine such as a film transport and an electrical control. As will be described later, the RAM 6 stores a control program for the DSP 7, input image data corresponding to R, G, and B from the CCD 8, 1DLUT created according to the input image data, and colors for the input image data by the DSP 7. Stored are processed data (output image data) subjected to various processes such as correction. The DSP 7 includes components using DMA (direct memory access) for data input / output, which will be described later. The DMA is a method for exchanging data between the input / output device and the memory without going through the CPU, and a component using the DMA (hereinafter simply referred to as DMA) is read from the CCD 8. Sending data (input image data) to the RAM 6, sending the data from the RAM 6 to various processing devices that perform color correction, returning the processed data to the RAM 6, and sending the processed data from the RAM 6 to the SCSI bus; Data transfer such as. The SCSI-C4 controls a SCSI interface that exchanges between the film scanner and an external device such as a personal computer. Each unit described above is connected to each other via an I / O bus (address bus, data bus, and control bus) 2.

  In this embodiment, SCSI is used as an interface with an external device such as a personal computer. However, the present invention is not limited to this. For example, communication with an external device is possible regardless of wired or wireless, such as USB and Bluetooth. Any interface that can do so can be used.

FIG. 2 is a block diagram showing a schematic configuration of a DSP according to an embodiment of the present invention.
In FIG. 2, the DSP 7 has DMAs 11 to 14 inside. The DMA 11 inputs data sent from the CCD 8 outside the DSP 7, the DMA 12 transfers data to the RAM 6 outside the DSP 7, the DMA 13 outputs data to the RAM 6 outside the DSP 7, and the DMA 14 is DSP 7. Data is transferred to the internal RAM 15 and the processors 16 to 19. Since the RAM 15 is inside the DSP, its capacity is limited and the capacity is smaller than that of the RAM 6, but it can be accessed faster than the RAM 6 outside. The RAM 15 stores input image data, data processed by the processors 16 to 19 and the like, as will be described later. The processors 16 to 19 are processing devices that perform various processes such as color correction. Each unit described above is connected to a bus for transmitting data.

  FIG. 3 is a diagram showing an internal configuration of the RAM 6 according to an embodiment of the present invention. In the same figure, the part to which each minus sign is attached is a memory area allocated for storing each data.

  In FIG. 3, a memory area 20 stores a program for controlling the DSP 7 (hereinafter also referred to as a DSP control program), and a program for performing various processes such as color correction is described here. The memory area 21 stores various variables necessary for executing processing. The memory area 22 stores input image data sent by an image input device such as the CCD 8 and output image data (processed data) obtained by processing various input image data such as color correction by the processors 16 to 19. Is done. From the memory area 23 (memory areas 23, 24, 25...), 1DLUT created for each of the R, G, and B channels for each input image is stored. In the figure, in the first frame image read by the CCD 8, the 1DLUT created for R is stored in the memory area 23, the 1DLUT created for G is stored in the memory area 24, and the 1DLUT created for B is They are stored in the memory area 25, respectively. In the second frame image, the 1DLUT created for R is stored in the memory area 26, and similarly stored in a predetermined memory area in accordance with the number of input image frames.

  FIG. 4 is a diagram showing an internal configuration of the RAM 15 according to the embodiment of the present invention. In the same figure, the part to which each minus sign is attached is a memory area allocated for storing each data.

  In FIG. 4, the memory area 30 stores a program for controlling the DSP 7. Since the DSP control program stored in the memory area 30 is in the DSP 7, processing can be performed at a higher speed than when the DSP control program stored in the memory area 20 shown in FIG. 3 is used. In the memory area 31, input image data necessary for processing, which is extracted from the memory area 22 of the RAM 6, is stored. The memory areas 32, 33, and 34 store the 1DLUT for R, the 1DLUT for G, and the 1DLUT for B, which are selected and extracted in accordance with the image to be processed from the memory area 23 of the RAM 6, respectively.

In this embodiment, the color information per pixel of the input image from the CCD 8 is 14 bits, and the color information per pixel of the converted output image is 16 bits. Therefore, when the processing in the DSP 7 is gradation conversion processing, gradation conversion processing with input 14 bits and output 16 bits is performed in 1DLUT processing. Therefore, if all the data of 1DLUT of each channel of R, G, and B is stored in the memory area, it becomes 2 ¹⁴ × 16 × 3 = 78632 bits, that is, 96 Kbytes. It does not fit in the internal RAM 15. Therefore, in order to store all 1DLUTs for the R, G, and B channels of the input image data in the RAM 15, it is not a method of having conversion values for all the data of the input image as table values, but a predetermined interval of all the data of the input image. Conversion values are stored in the memory only for the sampling points, and output values are calculated by interpolation calculation using the conversion values of the sampling points. That is, a 1DLUT with a small data amount can be created by sampling all data of the input image at a predetermined interval.

  In this embodiment, 14-bit input data 0 to 16383 are held as output conversion values as table values at predetermined intervals for every 16 counts. The reason for setting the predetermined interval to 16 counts is that division by shift operation is possible when the memory size and DSP 7 are set to a power of 2, and higher-speed processing can be performed. Therefore, in the present embodiment, the above-described count value is not limited to 16 counts and may be any value, but a power of 2 is preferable.

FIG. 5 is a diagram illustrating a lookup table according to an embodiment of the present invention.
In FIG. 5, since sampling points are determined every 16 counts, the table input values are X ₀ = 0, X ₁ = 16... X ₁₀₂₃ = 16368, X ₁₀₂₄ = 16383, and the corresponding output values are Y ₀ , Y ₁ ,... Y ₁₀₂₃ , Y _{1024 are} assumed.

Data other than the above sampling points is calculated by the interpolation calculation shown below.
An arbitrary input value is x (14 bits) and the output value at that time is y (16 bits).

At this time, k is the upper 10 bits of the input value x, the upper 10 bits of the address input value x of Y _k , and the value of (x−X _k ) is the value of the lower 4 bits of the input value x.

  In the present embodiment, the interpolation calculation according to Expression (1) can be performed using a dedicated circuit or software.

  Thus, the number of table data for each of the R, G, and B channels is 1025 / channel. Therefore, the memory area to be used is 1025 × 16 bits × 3 channels = 49200 bits, that is, about 6 Kbytes, which is a size that can be stored in the RAM 15, and that all the 1DLUTs for each color created as described above are stored in the RAM 15. Can do. In the present embodiment, since one DLUT is created for each frame, a maximum of about 40 frames of 1DLUT must be stored in the RAM 6 outside the DSP 7. Conventionally, if all data is stored in the memory area, it is necessary. Although the memory becomes 96K bytes x about 40 frames = about 3840K bytes, the necessary memory becomes 6K bytes x about 40 frames = about 240K bytes by performing the above interpolation processing. Save money.

  A procedure for storing 1DLUT created for each of the R, G, and B channels for each input image in the RAM 6 in order to perform color correction processing on the input image data by the CCD 8 will be described below.

FIG. 6 is a flowchart showing a procedure for storing the 1DLUT corresponding to the input image in the RAM 6 according to an embodiment of the present embodiment.
In FIG. 6, pre-scanning is performed in order to obtain information necessary for creating a 1DLUT necessary for color correction for each frame. When the pre-scan is performed, this procedure is started.

  In step 40, one frame of image data input by the pre-scan is input to the DSP 7.

  In step 41, a 1DLUT corresponding to the frame input by the data input in step 41 is created for each of the R, G, and B channels, and the created data is stored in a 1DLUT storage area after the memory area 23 of the RAM 6. . Although a known method can be adopted as a method for creating a 1DLUT, in this embodiment, for example, from the result of reading the luminance of a patch, input device profile data corresponding to the same patch is output as an output target. Create a lookup table to convert to the data.

  In step 42, it is determined whether there is a next frame. If there is still an image to be input, the process returns to S40, the next frame is input to the DSP 7, and the process is repeated to S41. If there is no next piece, this operation is terminated.

  In the present embodiment, a 1DLUT is created for each image prescan. However, the present invention is not limited to this. For example, the prescanned image is accumulated in a predetermined storage device, and the accumulated predetermined One DLUT may be created collectively for image data of the number of frames. In this case, the image data of a predetermined number of frames may be regarded as one group, and the storing procedure in the RAM 6 described with reference to FIG. 6 may be performed for each group.

  The timing for creating the 1DLUT is not limited to the timing described above, and any timing may be used as long as color correction is performed on the prescanned image.

  Furthermore, in this embodiment, the 1DLUT is created for each image captured according to the image captured by the pre-scan. However, the present invention is not limited to this, and a number of 1DLUTs are stored in a storage device such as the ROM 3 in advance. Alternatively, a 1DLUT suitable for input image data captured by the CCD 8 may be selected and used. At this time, the amount of data can be reduced by sampling the selected 1DLUT at predetermined intervals.

  Next, a procedure for color correction for an image corresponding to the created 1DLUT using the 1DLUT created for each input image according to FIG. 6 will be described.

FIG. 7 is a flowchart showing a procedure for color correction for input image data according to an embodiment of the present invention.
When the pre-scanned image is scanned to capture an image, this procedure is started.

  In step 50, the R, G, and B channels, which are 14-bit image data (input image data) captured by scanning, are input to the RAM 6 and stored in the memory area of the RAM 6.

  In step 51, the 1DLUT corresponding to the currently input image created at the time of pre-scanning is taken into the RAM 15 with high processing speed and stored in the memory area corresponding to each color.

  In step 52, in order to perform color correction processing, the input image data is fetched into the RAM 15 having a high processing speed and stored in the memory area 31.

  In step 53, based on the R, G, and B data for each pixel of the input image data captured in step 52, the above-described interpolation calculation formula for the output data output from the 1DLUT captured in step 51. Interpolation processing is performed using (1) to add color correction.

  In step 54, the output image data corrected in step 53 is sent from the RAM 15 to the RAM 6 and stored in the memory area 22.

  In step 55, it is determined whether or not color correction has been performed on all pixels of the input frame. If it is determined that color correction has not been performed on all the pixels of the input frame, the process returns to step 51, the corresponding image is fetched from the RAM 6 into the RAM 15, and color correction is performed on the uncorrected pixels of the image data. repeat. When it is determined that color correction has been performed on all the pixels of the input frame, the color correction for the input image data of one frame is completed, and the process proceeds to step 56.

  In step 56, it is determined whether or not there is an input for the next frame. If it is determined that there is an input for the next frame, the process returns to step 50 to repeat the color correction according to this procedure. If it is determined that there is no input for the next frame, this operation is terminated.

  Since the image data to be processed in this way is stored and processed in the internal memory of the DSP 7 as a processing device, especially when referring to 1DLUT, it refers to the external memory every time one pixel is processed. And the processing speed can be greatly increased.

  In this embodiment, a CCD is used as the image input device. However, any device may be used as long as it can capture input image data such as R, G, and B.

  In this embodiment, 14 bits are used as the information amount of R, G, and B per pixel of the input image data, and 16 bits are set as the information amount of the output image data. However, the information amount is limited to these information amounts. If, for example, the information amount of each of R, G, and B per pixel of the input image data is set to a value larger than the above 14 bits, such as 16 bits, the conversion table is increased accordingly. If the information amount of the input image data is set to a value smaller than 14 bits, the conversion table is made smaller accordingly and the sampling point is adjusted, so the number of input / output bits is any value. Also good. Further, even when color corrections such as C (cyan), M (magenta), Y (yellow), and K (black) are performed, the amount of information is reduced so that each input image can be stored in the internal memory of the DSP 7 as described above. The 1DLUT may be created and color correction may be performed for each pixel.

  In this embodiment, a film scanner is used as the image processing apparatus. However, the color correction is performed by inputting a color image signal or a color video signal, a scanner, a camera, a hard copy apparatus, a color display apparatus, a color corrector. Any other device that performs color correction, such as a video editing device and a color recognition device that performs color identification, may be used.

  Furthermore, in this embodiment, the input image color correction is performed as processing performed by the DSP 7. However, the present invention is not limited to this, and any configuration may be used as long as 1DLUT is required for processing by the DSP 7.

  As described above, according to this embodiment, 1DLUT is created for each image with respect to the input image data, and color correction is performed on each pixel of the input image, thereby performing more delicate color correction. By reducing the amount of data so that the 1DLUT created in the internal memory of the processing device can be stored, the processing speed can be increased and the cost can be reduced by reducing the memory.

1 is a block diagram showing a schematic configuration including peripheral devices of a film scanner that is an image processing apparatus according to an embodiment of the present invention. It is a block diagram which shows schematic structure of DSP which concerns on one Embodiment of this invention. It is a figure which shows the internal structure of RAM6 which concerns on one Embodiment of this invention. It is a figure which shows the internal structure of RAM15 which concerns on one Embodiment of this invention. It is a figure which shows the look-up table which concerns on one Embodiment of this invention. 4 is a flowchart showing a procedure for storing 1DLUT corresponding to an input image in a RAM 6 according to an embodiment of the present embodiment. It is a flowchart which shows the procedure for the color correction with respect to the input image data which concerns on one Embodiment of this invention.

Explanation of symbols

1 CPU
2 I / O bus 3 ROM
4 SCSI-C
5 Controller 6, 15 RAM
7 DSP
8 CCD
11, 12, 13, 14 DAM
16, 17, 18, 19 processor

Claims (10)

An acquisition process for acquiring image data;
A creation step of creating a one-dimensional lookup table (1DLUT) at sampling points at a predetermined interval based on the image data;
A storing step of storing the 1DLUT in an internal memory of a conversion processing unit that performs a conversion process using the 1DLUT;
An image processing method comprising: a conversion process step of converting the image data by performing an interpolation process on the output data output from the 1DLUT based on the image data by the conversion processing means.   2. The image processing method according to claim 1, wherein the image data is data captured by scanning of an image input means.   The image processing method according to claim 1, wherein the 1DLUT is for red, green, and blue.   The image processing method according to claim 1, wherein the predetermined interval is represented by a power of two.   The image processing method according to claim 1, wherein the conversion processing is color correction. Acquisition means for acquiring image data;
Creating means for creating a one-dimensional lookup table (1DLUT) at sampling points of a predetermined interval based on the image data;
Conversion processing means for converting the 1DLUT using the 1DLUT;
An internal memory included in the conversion processing means for storing the 1DLUT;
An image processing apparatus comprising: conversion processing means for performing an interpolation process on output data output from a 1DLUT based on the image data by the conversion processing means to convert the image data.   The image processing apparatus according to claim 6, wherein the image data is data captured by scanning of an image input unit.   The image processing apparatus according to claim 6, wherein the 1DLUT is for red, green, and blue.   The image processing apparatus according to claim 6, wherein the predetermined interval is expressed by a power of two. The image processing apparatus according to claim 6, wherein the conversion process is color correction.

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