KR101314826B1 - Method for displaying focus position of image when digital image processing device plays storing image - Google Patents

Abstract

The present invention relates to a method of operating a digital image processing apparatus, and more particularly, to a method of showing a focus point when reproducing an image stored in a digital image processing apparatus. A method of displaying a focus point of an image in a reproduction mode is a method of reproducing an image stored in a digital image processing apparatus. The method includes dividing an image being displayed into a predetermined number of blocks and having a maximum AF value from luminance data of the divided blocks. After searching for, the block having the maximum AF value is separately displayed and displayed together with the image.

Description

Method for displaying focus position of image when digital image processing device plays storing image}

1 is a diagram in which a captured image is reproduced on a display unit.

2 is a block diagram illustrating a configuration of a digital image processing apparatus for capturing an image.

3 is a flowchart illustrating an operation of a method of displaying a focus point of an image in a playback mode in the digital image processing apparatus of FIG. 2 according to the present invention.

4 is a waveform diagram for explaining the execution of AF (autofocus).

FIG. 5 is a diagram illustrating an image divided into m × n blocks for displaying a focus point of an image in FIG. 3.

6 is a diagram illustrating a focus point of an image displayed on a display unit in a playback mode according to FIG. 3.

The present invention relates to a method of operating a digital image processing apparatus, and more particularly, to a method of showing a focus point when reproducing an image stored in a digital image processing apparatus.

One of the conveniences of the digital camera as a digital image processing device compared to the film camera is that the captured image can be immediately checked in the field and re-determined.

The user checks the captured image as shown in FIG. 1 through the display unit attached to the digital image processing apparatus. Since the size of the display unit is insufficient to observe the captured image in detail, it was considered a satisfactory result. May be disappointed later on the PC monitor. In particular, it is difficult to accurately grasp information such as brightness, contrast, color, and focus of an image on a display.

Among them, brightness, contrast, and color are not a big problem because they can be adjusted within a certain range through post-correction due to the characteristics of digital photos, but focus is not corrected by post-correction. Be particularly careful.

If you take a picture with AF (Auto focus), the display will show the focus point, but if the digital image processing unit shakes or moves with the AF lock immediately before shooting, it will not be the focus point displayed on the screen. Will be in focus. This is especially the case with macro photography. In playback mode, you can enlarge the image to check the result, but it is very inconvenient to check all the images one by one, and in the digital image processing device with the continuous shooting function, the image of the same scene Many are particularly uncomfortable.

In addition, in case of DSLR (Digital Single Lens Reflex), the front pin phenomenon or the rear pin phenomenon may appear collectively due to mechanical error or the characteristics of the lens. This can only be observed through.

When photographing with manual focus, the focus point is determined by the visual judgment of the photographer while looking through the viewfinder or the display unit, which is inconvenient because there is no way to check whether the result of the photographing is focused as desired.

As described above, in the conventional digital image processing apparatus, it is difficult to accurately determine the point where focus is achieved by the image displayed on the display, and thus, it does not provide an opportunity for re-photographing when the focus is not achieved as intended. For this reason, many users offer AF bracketing to shoot multiple shots of the same scene, or some digital image processing devices to take multiple shots with different focus on the same scene. Eventually, there is an inconvenience in that post-production has to take much more images than the types of scenes to be photographed and to select a desired image from the photographed images.

The technical problem to be solved by the present invention is to divide a display unit size image into m × n blocks and retrieve a block having the maximum AF value from the luminance data of each block when the image stored in the digital image processing apparatus is reproduced. The present invention provides a method of displaying a focus point of an image in a playback mode in a digital image processing apparatus displaying the selected image together with the selected image.

A method of displaying a focus point of an image in a playback mode in a digital image processing apparatus for solving the technical problem to be solved by the present invention is a method of reproducing an image stored in a digital image processing apparatus. A method of playing a video, comprising: (a) dividing an image being displayed into a predetermined number of blocks; (b) retrieving a block having a maximum AF value from the luminance data of the blocks; And (c) separately displaying the block having the maximum AF value and displaying the block together with the image.

In the present invention, at least one or more blocks having a maximum AF value within a predetermined tolerance range are searched for when the block having the maximum AF value is searched.

In the present invention, after retrieving the block having the maximum AF value separately indicated, it is determined whether to retake the image.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram showing the configuration of a digital image processing apparatus for capturing an image, and includes a user input unit 201, an image capturing unit 203, an image processing unit 205, a storage unit 207, a display unit 209, and a digital display. A digital signal processor (DSP) 211 is included.

The user input unit 201 is opened and closed to expose a charge coupled device (CCD) or film to light for a predetermined time, and interlocks with an aperture (not shown) to properly expose a subject to record an image on the CCD. Second shutter release buttons S1 and S2 (not shown), and function buttons (not shown) for inputting various menus.

The imaging unit 205 includes a shutter, a lens unit, an aperture, a CCD, and an ADC not shown in the figure. The shutter is a mechanism that adjusts the amount of light that is exposed with the iris. The lens unit receives light from an external light source and processes an image, and includes a zoom lens, a focus lens, and a compensation lens. At this time, the iris adjusts the amount of light incident (light quantity) according to the degree of opening and closing. The opening / closing degree of the diaphragm is controlled by the digital signal processing section 211.

In performing AF, a focus motor (not shown) for moving the focus lens is driven by the digital signal processor 211. As a result, the focus lens is moved from the front to the rear, and in this process, the position of the focus lens where the high frequency component of the image signal is the greatest, for example, the number of driving steps of the focus motor is set.

The CCD accumulates the amount of light input through the lens unit and outputs the image captured by the lens unit according to the accumulated light amount in accordance with the vertical synchronization signal. Image acquisition of the digital image processing apparatus is performed by a CCD that converts light reflected from a subject into an electrical signal. In order to obtain a color image using a CCD, a color filter is required, and most of them employ a filter (not shown) called a color filter array (CFA). CFA has a regularly arranged structure that passes only light that represents one color per pixel, and it has various forms according to the arrangement structure. The ADC converts the analog video signal output from the CCD into a digital signal.

The image processor 205 performs signal processing to display a digitally converted image signal. Devices used in CCD and CFA filters are sensitive to changes in temperature and generate a dark current according to the changed temperature, which includes an unwanted black level in the image signal. Thus, the image processor 207 removes the black level generated by the dark current in this way.

The image processor 205 also performs gamma correction. Since human vision reacts nonlinearly to brightness according to Weber's law, when a limited bit depth is given, linearly recording the brightness of the light can cause posterization. This happens. Therefore, in order to show the maximum image quality under a given bit depth, it is necessary to encode using a nonlinear function. As described above, encoding information in accordance with nonlinearity of human vision is referred to as gamma correction. The gamma correction of the image processor 205 gamma corrects and outputs an image signal input by the gamma curve. For example, the input luminance level of a 12 bit image signal is corrected to an 8 bit luminance level and output.

The image processor 205 performs CFA interpolation to interpolate the Bayer pattern implemented by the RGRG line and the GBGB line of the gamma corrected predetermined data into the RGB line. CFA interpolation of the image processing unit 205 first reconstructs the G channel from pixels having only the R or B channel value, and then fills the empty values in the B channel, the R channel order, or the R channel and the B channel order. G, B Restore three channels.

The image processing unit 205 converts the interpolated RGB signal into a YUV signal, filters the Y signal by a high band filter, and performs edge compensation to process the image clearly, and uses the standard color coordinate system to adjust the color values of the U and V signals. Perform color correction to correct and remove their noise.

The image processor 205 compresses and signals the Y, U, and V signals from which the noise is removed to generate a JPEG file, and the generated JPEG file is stored in the storage unit 207 by user selection.

When an image stored in the storage unit 207 is selected by an input of a function button at the time of image reproduction, the image processing unit 205 converts the selected JPEG image into YCC data and displays it on the display unit 209. The size of the display unit 209, for example, 640 × 480, is converted and displayed. All of the operations of the image processor 205 operate under the control of the digital signal processor 211. In addition, the operation of the image processor 205 will be described with reference to FIG. 3.

Hereinafter, a method of displaying a focus point of an image in a reproduction mode in the digital image processing apparatus according to the present invention will be described in detail with reference to FIGS. 2 to 6. According to an embodiment of the present invention, the main algorithm of the control method may be performed inside the digital signal processor 211 with the help of peripheral components in the control device.

After the user operates the power of the digital image processing apparatus, if the photographing mode is selected, the YCC image data in the preview state is displayed on the display unit 209 (step 301). The preview image is an image appearing on the display unit 209 immediately before capturing the still image, and is processed quickly because it is 1/6 or less of the captured data. In order to display the preview image, the image processing unit 205 extracts YCC data from the preview image input through the imaging unit 203 under the control of the digital signal processing unit 211 and converts the YCC data to fit the size of the display unit 209. Display on the display unit 209

 In the state where the preview image is displayed on the display unit 209, the user sets a desired composition (step 303) and inputs the first shutter release button S1 (step 305).

When the first shutter button S1 receives the input signal, the digital signal processor 211 executes auto focus (step 307). 4 is a waveform diagram illustrating the auto focus. Auto focus refers to automatically measuring the distance between the digital image processing apparatus and the subject and moving the focus lens to focus. Whether the image is in focus or not can be distinguished by how many high frequency components the luminance signal of the image has. In the unfocused image, the part of the outline including the high frequency component is blurred, and the part of the outline etc. in the focused image is clearly seen. In other words, the unfocused image has low luminance data including the high frequency component, while the focused image contains the high frequency component including the high frequency component. Therefore, autofocus is performed by obtaining the AF value using the luminance data for one field and moving the position of the focus lens toward the larger value. The arrow shown in FIG. 4 means to search to move the focus lens to the part where focus is best achieved.

When the auto focus execution is completed by the input of the first shutter button S1, the user inputs the second shutter button S2 to capture an image (step 309).

With respect to the image photographed by the input of the second shutter button S2, the digital signal processor 211 controls the image processor 205 to convert the image into a JPEG image by signal processing the image as described above, and then stores the image. 207).

Thereafter, when the user selects an image stored in the storage unit 207 by using a function button, the digital signal processor 211 loads the selected JPEG image (step 313).

When an image for image reproduction is selected, under the control of the digital signal processor 211, the image processor 205 converts the JPEG image into YCC image data to fit the size of the display unit 209 (step 315).

Thereafter, the image processor 205 divides the YCC image data having the size of the display unit 209 into m × m blocks (step 317). FIG. 5 shows a diagram of dividing YCC image data having a size of the display unit 209 into m × m blocks having a size of (x × y).

Subsequently, the digital signal processor 211 retrieves the maximum AF value from the luminance Y data of the m × m blocks (step 319). In this case, the digital signal processor 211 searches for one or more blocks having the maximum AF value within a predetermined tolerance range together. For example, if the maximum AF value is found to be 20 and the tolerance is ± 0.5, even if the AF value is 19.5 or 20.5, the maximum AF value is found. Since AF is sensitive to luminance, it is difficult to retrieve the AF value at low luminance. However, since the image processing unit 205 performs gamma correction once the image is captured, the AF value can be searched more easily when the image is reproduced.

When a block indicating at least one maximum AF value is found, under the control of the digital signal processor 211, the image processor 205 separately displays the searched block and displays it on the display unit 209 along with the YCC image (321). step). 6 illustrates a focus point of an image displayed on the display unit 209 in the playback mode. The existing digital image processing apparatus does not have a function of checking an AF point as shown in FIG. 1 in the playback mode. The user can know the AF point only at the moment of capturing the image (at the time of inputting the first shutter release button S1), and also cannot know whether it matches the actual result. However, the present invention, as shown in Figure 6, since the AF point is displayed together in the playback mode, it is possible to easily identify the AF point difficult to confirm through the display unit 209. In particular, in the case of a macro image with a shallow depth of field, since the AF point greatly affects the picture quality, it is very useful to use the present invention.

The user checks the AF point displayed on the display unit 209 and determines whether to retake the image (step 323).

In the case of AF applied in image capturing, focus motor control and algorithmic complexity are required for fast AF speed and accuracy, but focus motor control is not required for an image (fixed data) that has already been captured. Y) Since only the maximum AF value needs to be found in the data, more granular blocks can be applied and thus more accurate AF points can be found.

Since the playback image used to find the AF point uses the same image (640 × 480) as the size of the display unit 209, the operation can be performed in a short time, and the user can input the desired function button to confirm the AF point. Can be implemented.

As described above, when the image stored in the digital image processing apparatus is reproduced, the display unit size is divided into m × n blocks, and the block having the maximum AF value is searched separately from the luminance data of each block. By displaying the image together with the selected image, the focus point can be checked at a glance, so it is easy to determine whether or not re-photographing is necessary.

In the case of continuous shooting with a large number of shots, it is possible to check the focus point even while flipping the video at high speed, enabling quick image checking.

Since the digital image processing apparatus is equipped with hardware for focus detection calculation during AF, if applied to the image inversely, the focus information on the photographing result can be obtained and displayed on the display unit so that it can be easily applied without any additional device. It is possible.

The present invention has been described with reference to the preferred embodiments. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Claims (3)

A method of playing back an image stored in a digital image processing apparatus, Steps to Display the Recorded and Stored Image Dividing the image being displayed into a predetermined number of blocks; Retrieving a block having a maximum AF value from the luminance data of the blocks; And And separately displaying the block having the maximum AF value and displaying the block together with the image. The method of claim 1, wherein the search for the block having the maximum AF value is performed. A method of displaying a focus point of an image in a playback mode in a digital image processing apparatus, characterized by searching for at least one or more blocks having a maximum AF value within a predetermined tolerance range. The method of claim 1, wherein after retrieving the block having the separately displayed maximum AF value, it is determined whether to retake the image.

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