JP2003141532A - Image processing apparatus and method, printer, and storage medium storing computer readable program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direct printer capable of easily performing printing of high quality without placing a burden on the user regarding a determination as to whether image processes should be applied, nor dropping printing speed more than needed. SOLUTION: The printer has at least the function of generating image data by expanding compressed image data and the function of performing resizing printing according to the image data. Based on the degree of compression of the compressed image data and/or the degree of resizing during printing, the application of image processes (noise elimination process, sharpness process) to the image data is automatically controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer having a function of expanding image compressed data to generate image data and executing printing (for example, size conversion printing) based on the image data.

[0002]

2. Description of the Related Art Conventionally, when printing an image picked up by a digital camera or the like at home, first, the image data is transferred from the digital camera or the like to a personal computer, and the personal computer is operated to print from a printer connected to the personal computer. It was generally performed in a printing form called "do."

Recently, however, the number of users who purchase digital cameras has been diversified, and the number of users who have digital cameras but not personal computers is increasing. Therefore, a printer (hereinafter, referred to as "direct printer") capable of directly printing an image by itself without using a host device such as a personal computer has been proposed and its development has been advanced.

As a configuration of the direct printer, for example, a configuration having a standard PC card slot as an interface can be considered. In this case, set the flash memory used for recording in digital cameras etc. in the PC card adapter and insert it in the PC card slot.
In the direct printer, an image is read from the flash memory and printing is executed. As another configuration, instead of the PC card slot, a configuration in which a digital camera and a direct printer are directly connected by a USB or the like can be considered.

By the way, in a digital camera or the like, in order to secure as many image-capturing images as possible, it is general that the captured images are data-compressed and stored in a flash memory. , JP
EG (Joint Photographic Expert Group) is widely adopted.

[0006] JPEG is known as a method capable of effectively compressing scenery, photographic data, etc.
A method of truncating a part of information in the compression process (Lossy),
There is a lossless method from the original image (Lossless), but digital cameras often use the Lossy method.

In the general Lossy system, the input image is first divided into blocks of 8 × 8 pixels, and D is divided into blocks.
Perform CT calculation. Then, for the obtained DCT coefficient,
The DC component (DC component) and the AC component (AC component) are independently quantized, and the coefficient of the DC component is encoded by the difference value with the DC component coefficient of the immediately preceding block as the predicted value.
For the coefficient of the AC component, run length compression and Huffman coding are performed. Information loss will occur in the above quantization.

[0008]

When printing an image picked up by a digital camera or the like, the image may be deteriorated due to the following reasons.

The first is image deterioration caused by the characteristics of the image sensor. When a CCD (charge coupled device) is used as an image sensor, noise called dark current noise (thermal noise) becomes a problem. Such noise tends to be more likely to be recorded, especially as the exposure time (shutter speed) is longer. On the other hand, in low-priced digital cameras, CMOS (complementary metal oxide semiconductor) is often used as an image sensor. This is because the CMOS image sensor can be integrated, has the features of a single power supply and low power consumption, and can reduce the cost as compared with the CCD. However, the CMOS image sensor tends to be an image with much noise as compared with the CCD because of a decrease in sensitivity accompanying miniaturization.

The second is image deterioration caused by the characteristics of the compression system. JPEG generally adopted as a compression method
Has a deterioration characteristic that noise called mosquito noise or the like is generated in an image including a high frequency component or an edge portion when the compression rate is increased and the file capacity is reduced.

The third is image deterioration caused by the number of pixels. In low-priced digital cameras, the number of effective pixels of the image sensor is often about 300,000 to 1,000,000 pixels. In this case, for example, when trying to print with a relatively large size such as A4 size, the dot density becomes small with the number of pixels as it is. Therefore, usually, size conversion such as replacing one pixel with a plurality of pixels is performed to change the dot density. Printing is performed by raising the printing (hereinafter, such printing is referred to as "enlarged printing"). However, in such enlarged printing,
The more the image is enlarged, the more blurred the edge or the like is, and the image is greatly deteriorated.

When such image deterioration occurs, in order to print the image with good quality, appropriate image processing (for example, noise removal processing and sharpness processing) is performed.
It is important to apply Here, in the case of printing via the host device, the above-described image processing can be performed at high speed in the host device having high processing capability, but in the case of the direct printer, the printer itself performs these image processing. Need to do.

However, in general, the C mounted on the printer is used.
Since the PU has a lower processing capacity than that of a personal computer or the like, if a configuration is adopted in which image processing is always applied and printing is performed, there is a problem in that the printing speed is reduced.

On the other hand, when the user judges the necessity of the image processing and selectively applies the image processing under the instruction of the user, the printing speed is increased even when the image processing is unnecessary. It is possible to prevent the deterioration. However, forcing the user to make such a judgment imposes a heavy burden on the user (particularly, a user who is not familiar with image processing and the like), and it is not possible to satisfy the needs for printing easily and easily.

Therefore, an object of the present invention is to provide a direct printer which can easily perform high-quality printing without burdening the user and without unnecessarily reducing the printing speed.

[0016]

A printer of the present invention has a function of decompressing compressed image data to generate image data,
A printer having at least a function of performing size conversion printing based on image data, the image data being based on the degree of compression in the image compression data and / or the degree of size conversion at the time of printing. It is characterized by controlling the application of image processing to.

The printer of the present invention is a printer having at least a function of expanding image compressed data to generate image data and executing printing based on the image data, and the degree of compression in the image compressed data. The application of image processing to image data is controlled based on

Further, the printer of the present invention is a printer having at least a function of executing size conversion printing based on image data, and applies image processing to the image data based on the degree of size conversion at the time of printing. It is characterized by controlling.

Preferably, the noise removal processing is applied when the degree of compression is high. In this case, it is desirable to change the degree of noise removal according to the degree of compression.

Further, preferably, when printing is performed with an enlarged size, the sharpness processing is applied when the degree of enlargement is large. In this case, it is desirable to change the degree of sharpness enhancement according to the degree of enlargement.

Further, preferably, the printer of the present invention is configured to be capable of reading image compressed data from an external memory or an electronic device electrically connected and executing printing without going through a host device. It is characterized by

The printing method of the present invention is a printing method including at least the steps of expanding image compressed data to generate image data, and executing size conversion printing based on the image data. The method is characterized by comprising the step of controlling the application of image processing to the image data based on the degree of compression and / or the degree of size conversion when printing.

The printing method of the present invention can be carried out by a computer, and the computer program therefor can be installed or loaded into the computer through various media such as a CD-ROM, a magnetic disk, a semiconductor memory and a communication network. You can

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the hardware configuration of the printer 1 of this embodiment.

The printer 1 includes a paper feed feeder 10 for feeding paper into the printer, a print engine 11 for printing,
And a power mechanism unit 2 including a paper discharge feeder 12 for discharging the paper to the outside of the printer.

It is the CPU (processor) 13, the ROM 14 and the ROM 14 that control the power mechanism section 2 to perform the printing operation.
RAM15, LCD panel and LCD controller 1
6, a printer control unit 3 including a communication interface 17 and the like. The CPU 13 uses various means 14 via the internal bus.
To 17 are accessible, and the power mechanism unit 2 is controlled according to a print job sent from the host device via the communication interface 17 to actually perform the printing operation. Note that the power mechanism unit 2 may independently include a CPU, and in that case, the CPU of the power mechanism unit 2
However, it communicates with the CPU 13 via a parallel interface or the like to control the print engine 11 to perform the printing operation.

The structure and operation of the power mechanism unit 2 and the printer control unit 3 are basically the same as the structure and operation of the conventional printer device. However, in the printer 1, the printer control unit 3 further includes a PC card slot and a PC card controller 18, and image compression data such as a JPEG file is read from an external memory via the PC card slot 18 and the like, which will be described later. It is configured so that printing can be performed by performing decompression processing and size conversion processing according to the image processing application control flow (hereinafter, such a printing operation that does not go through a host device is referred to as "direct printing"). 2 shows a functional configuration diagram in the printer control unit 3 for realizing the direct printing. As shown in the figure, the printer control unit 3 includes a panel IF unit 20, a PC card IF unit 21, an expansion unit 22, and a size conversion unit 2.
3, an image processing unit 24, a control unit 25 and the like. Each of the above means is functionally realized by the CPU 13 executing an application program stored in the memory.

The panel IF means 20 receives commands from the user to the printer 1 via the LCD panel composed of an LCD and operation keys and the LCD controller 16, and outputs the print status and the like to the user. . The command received from the user may be, for example, a command (direct print command) requesting execution of the above-described direct printing.

The PC card IF means 21 is connected to the PC via the PC card slot and the PC card controller 18.
Data is read / written from / to an external memory (for example, a flash memory such as CompactFlash (registered trademark) or smart media) mounted on the card adapter.

The decompressing means 22 decompresses the image compressed data to decompress the image data. A well-known process corresponding to the compression method can be used for the decompression process. For example, when the compressed image data is a JPEG file,
For each 8 × 8 block, Huffman code decoding and run-length compression decoding are performed on the AC component, inverse quantization is performed with the DC component to calculate the frequency distribution, and inverse DCT is performed on the frequency distribution. , Restore image data.

The size conversion means 23 performs size conversion (enlargement / reduction) processing on the restored image data. The enlargement process can be realized simply by replacing one pixel with a plurality of pixels according to the enlargement ratio. However, in order to make the image after enlargement smooth, it is desirable to interpolate and determine the pixel value after enlargement based on the pixel value before enlargement. Examples of interpolation methods include the nearest neighbor method, bilinear method, and hypercubic method. On the other hand, the reduction processing can be realized by replacing a plurality of pixels with one pixel according to the reduction rate. The pixel value after reduction may be, for example, an average value of a plurality of pixel values before reduction.

The image processing means 24 performs image processing such as noise removal processing and sharpness processing on the restored image.

As a noise removing method, an existing method such as a method using a low-pass filter or a method using a median filter can be used. Also,
As the sharpness processing method, an existing method such as a method using an unsharp mask or a method using a Laplacian filter can be used.

Since the size of noise that can be removed depends on the size of the noise removal filter, it is desirable to store filters of a plurality of sizes so as to deal with various types of noise. From this viewpoint, the image processing unit 24 is configured to select the filter size according to the situation and perform the noise removal processing.

Further, it is desirable to perform sharpness processing more appropriately according to the degree of blur, such as sharpening more strongly when the blur is severe. The degree of sharpness can be controlled by the degree of emphasis of high frequency components. From this point of view, the image processing unit 24 is configured to perform the sharpness processing by changing the emphasis degree of the high frequency component according to the situation.

The control means 25 controls the application of image processing when executing direct printing. Hereinafter, the operation of the control unit 25 will be described together with the processing flow of direct printing with reference to the flowchart shown in FIG. It should be noted that each step can be executed by arbitrarily changing the order as long as the processing content does not conflict.

(Processing Flow of Direct Printing) In the direct printing, when the panel IF unit 20 receives a direct printing command from the user, the processing is started. At this time, when a plurality of compressed image data are stored in the external memory, for example, those file names are set to L
A list is displayed on the CD panel or the like 16, and the user is allowed to select a desired item from the list. When the printer 1 can execute the size conversion printing, the user receives the designation of the print size (for example, A4, B4, etc.). In addition,
In the following description, the description will be continued on the assumption that size conversion printing can be executed.

The PC card IF means 21 refers to the external memory via the PC card slot 18 or the like, and acquires the image data after decompression (before compression) and the size of the image compression data for the selected image compression data. Yes (S101). When the compressed image data is a JPEG file, the size of the restored image data is stored in the header portion of the JPEG file. Therefore, the size of the uncompressed image data can be acquired by referring to the header portion. . On the other hand, the size of the compressed image data is FAT (Fi) if the OS is Windows (registered trademark), for example.
It can be obtained by referring to (le Allocation Table).

The control means 25 calculates the compression rate = (image compression data size) / (image data size after restoration) based on the acquired image data size after restoration and image compression data size (S102). And compression rate <
It is determined whether or not T1 is established (S103). If so, it is determined that the image data after decompression may contain a lot of noise because the degree of compression is high, and the noise removal flag is turned on. It is set (S104). On the other hand, if the condition is not satisfied, it is determined that the degree of compression is low and noise removal is unnecessary, and the noise removal flag is set to OFF (S105). The threshold T1 can be set in advance according to the design, and may be set to, for example, 0.03 to 0.5.

Next, the control means 25 reads out the stored print size, and calculates the enlargement ratio as the degree of size conversion of both based on the acquired restored image data size and the read print size ( S106).

The enlargement ratio can be obtained as follows.

First, the print resolution (dpi) set in the printer 1 is referred to, and the size of the obtained image of the restored image data size that has been printed without size conversion is obtained. For example, the print resolution is 3
In the case of 00 dpi, the image data size is (640 pixels,
480 pixels), the size when printed as is is approximately (640/300 x 2.5 cm, 480 /
300 × 2.5 cm) ≈ (5.3 cm, 4 cm).

Next, the vertical enlargement ratio = (vertical length of the read print size) / (vertical length when the acquired restored image data is directly printed without size conversion), horizontal The enlargement ratio is calculated according to the enlargement ratio = (horizontal length of the read print size) / (horizontal length when the acquired restored image data is directly printed without size conversion).

The control means 25 determines whether (vertical enlargement ratio> T2) and / or (horizontal enlargement ratio> T3) is satisfied (S107). If yes, the degree of expansion is high,
When it is determined that blurring will occur remarkably when printed, the sharpness flag is set to ON (S108). On the other hand, if not satisfied, it is determined that the degree of enlargement is low and that sharpness is unnecessary, and the sharpness flag is set to OFF (S109). The thresholds T2 and T3 can be set in advance in accordance with the design, and are, for example, 3 to 1 respectively.
It is possible to set it between 0.

Next, the PC card IF means 21 refers to the external memory via the PC card slot 18 or the like to obtain the selected image compression data (S110). When the compressed image data is a JPEG file, it may be partially acquired in block units or block line units.

Next, the decompression means 22 decompresses the obtained image compressed data to decompress the image data (or a part thereof) (S111).

Next, the control means 25 determines whether or not the noise removal flag is ON (S112).
If it is ON, the image processing means 24 performs noise removal processing on the restored image data (or a part thereof) (S113). At this time, when a plurality of noise removal filters are stored, for example, the filter size is selected and used according to the acquired image data size after restoration and the calculated compression rate. FIG. 4 shows an example of filter size selection criteria.

In the example shown in the figure, the filter size is set to be larger as the compression rate is higher and the image data size is larger. This is set so that the size of the mosquito noise or the like changes depending on the degree of the compression ratio, so that a filter having an appropriate size is selected according to the size of the noise. Also, when the image data size is large (or small), the edge interval becomes relatively large (or small), so it is set so that a filter of an appropriate size is selected according to the edge interval. is there.

Next, the control means 25 determines whether or not the sharpness flag is ON (S11).
4). If it is ON, the image processing means 24 performs sharpness processing on the restored image data (or a part thereof) from which noise has been removed (S11).
5). At this time, the degree of emphasis is changed according to the calculated enlargement ratio, and the sharpness processing is performed. For example, when sharpening is performed using a Laplacian filter, the processed density value g (i, j) at the point (i, j) in the image is calculated using the unprocessed density value f (i, j). Is given by the formula. Note that ∇ ² f (i, j) represents the Laplacian at the point (i, j).

G (i, j) = f (i, j) −a × ∇ ² f (i, j) In the above equation, a is a coefficient representing the degree of enhancement, and the coefficient a is used to determine the degree of sharpness. Can be controlled. FIG. 5 exemplifies the standard for determining the coefficient a.

The order of image processing can be determined according to the design. For example, the image processing may be performed in the order of sharpness processing and noise removal processing. Further, it may be configured to apply either one of the image processings according to a predetermined condition. For example, it is conceivable that the edge strength is obtained, and when the edge strength is low, the noise removal processing is performed, and when the edge strength is high, the sharpness processing is performed.

Next, the size conversion means 23 performs a size conversion process on the restored image data (or a part thereof) subjected to the noise removal process and the sharpness process according to the read print size. Apply (S116).

Next, the image processing means 25 performs predetermined image processing (for example, color conversion processing, dither processing such as error diffusion method, etc.) that is usually performed in the printing operation on the image data that has undergone the size conversion processing. Then, print data is generated (S117).

Finally, the print data generated in this way is sent to the print engine 11 by the printer control unit 3 and printing is executed in the power mechanism unit 2 (S1).
18).

When the image compression data is partially acquired in S110, S110 to S117 are repeated until the processing is completed for all the image compression data. Further, in this case, the sequentially generated print data may be sequentially sent to the print engine 11, and printing may be executed in parallel with the generation of the print data.

As described above, the image deterioration condition due to noise is judged based on the compression ratio of the image compressed data, and the application of the noise removal processing is automatically controlled based on such judgment. It is configured to judge the image deterioration situation due to blurring based on the enlargement ratio of, and to automatically control the application of sharpness processing based on such judgment, so if the image is deteriorated, image processing is applied, As a result, high image quality can be achieved, and when the image is not deteriorated, the image processing is not applied, and as a result, the printing processing can be speeded up.

(Second Embodiment) Next, a second embodiment of the present invention will be described. The second embodiment includes a recording medium recording a control program. The recording medium may be a recording medium such as a CD-ROM, a magnetic disk, a semiconductor memory or the like, and includes a case where it is distributed as a printer card or a printer option board.

The control program is read from the recording medium into the information processing apparatus and controls the operation of the information processing apparatus. The information processing apparatus executes the same processing as the processing by the printer control unit 3 (or part thereof) in FIG. 1 under the control of the control program.

(Others) The present invention is not limited to the above-described embodiment, but can be variously modified and applied. For example, in the above embodiment, the application is controlled for both the noise removal processing and the sharpness processing, but the application may be controlled for only one of them.

Further, for example, in the above embodiment, image processing such as noise removal and sharpness processing is first applied,
Although it is configured to perform size conversion processing after that,
The order may be reversed, the size conversion processing may be performed first, and then the image processing may be applied. Furthermore,
It is conceivable that the image processing is applied first in the case of the enlargement processing and the size conversion processing is performed in the case of the reduction processing. The configuration in which the image processing is applied to the image data of a smaller size can be performed at high speed because the filtering range is small, and the effect of the image processing is large if the filters of the same size are used. is there.

Further, for example, in the above embodiment, the degree of sharpness is controlled according to the enlargement ratio, but the degree of sharpness is controlled not only according to the enlargement ratio but also the reduction ratio. May be.

Further, for example, in the above embodiment, the image compression data is acquired via the PC card slot or the like, but the image compression data may be received from the host device or a predetermined server via the communication interface. Good. In addition, electronic devices such as digital cameras
The image compression data stored in the electronic device may be directly read by connecting to the printer with a cable such as.

Further, for example, in the above-described embodiment, the function of printing based on the print job sent from the host device is provided, but it is also possible not to have such a function and to provide only the direct printing function.

Note that the printer of the present invention and the usage form of the technology are not limited to home use. For example, the printer is installed in a convenience store or the like, and the user brings an external memory or electronic device to A usage form such as printing is also conceivable.

[0065]

According to the present invention, the printer control unit performs image processing (noise removal, sharpness processing, etc.) on image data based on the degree of compression in image compressed data and the degree of size conversion in printing. Since the configuration is automatically controlled, it is possible to easily perform high-quality printing without burdening the user and without unnecessarily reducing the printing speed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a hardware configuration of a printer according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a functional configuration diagram of a printer control unit according to the first embodiment.

FIG. 3 is a flowchart showing a processing flow of direct printing.

FIG. 4 is a diagram showing criteria for selecting a filter size of a noise removal filter according to a compression rate.

FIG. 5 is a diagram showing a reference for controlling a degree of sharpness enhancement according to an enlargement ratio.

[Explanation of symbols]

1 printer 2 power mechanism 3 Printer control unit 10 paper feed mechanism 11 Print engine 12 Paper ejection mechanism 13 CPU 14 ROM 15 RAM 16 LCD panel and LCD controller 17 Communication interface 18 PC card slot and PC card controller 20-panel IF means 21 PC card IF means 22 Extension means 23 Size conversion means 24 Image processing means 25 Control means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G06T 5/00 300 G06T 5/00 300 5C078 9/00 9/00 H04N 1/393 H04N 1/393 1 / 40 1/41 Z 1/41 1/40 101Z F term (reference) 2C087 AA18 BC12 BD06 BD24 BD40 5B021 AA01 BB12 KK02 5B057 AA11 CA01 CA08 CA12 CB01 CB08 CB12 CC02 CE02 CE03 CG02 5C076 AA21 AA22 BA77 CB02 506 BB02 5 PP20 PQ20 SS02 TT02 5C078 BA57 CA22 DA02

Claims (11)

[Claims] 1. A printer having at least a function of decompressing compressed image data to generate image data and a function of executing size conversion printing based on the image data, the degree of compression of the compressed image data Based on or /
And a printer that controls the application of image processing to image data based on the degree of size conversion when printing. 2. A printer having at least a function of decompressing compressed image data to generate image data and executing printing based on the image data, the image being generated based on the degree of compression in the compressed image data. A printer characterized by controlling application of image processing to data. 3. The printer according to claim 1, wherein the noise removal processing is applied when the degree of compression is high. 4. The printer according to claim 3, wherein the degree of noise removal is changed according to the degree of compression. 5. A printer having at least a function of executing size conversion printing based on image data, wherein the application of image processing to image data is controlled based on the degree of size conversion at the time of printing. Characteristic printer. 6. The printer according to claim 1, wherein the sharpness processing is applied when the size is enlarged and the degree of enlargement is large. 7. The printer according to claim 6, wherein the degree of sharpness enhancement is changed according to the degree of enlargement. 8. The printer is configured to be capable of reading image compressed data from an external memory or an electronic device electrically connected and executing printing without passing through a host device. Claims 1 to 8
The printer according to any one of 1. 9. A printing method comprising at least a step of decompressing image compressed data to generate image data and executing size conversion printing based on the image data, the method being based on a degree of compression in the image compressed data. Or /
And a method of controlling application of image processing to image data based on a degree of size conversion at the time of printing. 10. A computer-readable recording medium that stores a program for executing the printing method according to claim 9 on a computer. 11. A program for causing a computer to execute the printing method according to claim 9.