1. Field of the Invention
The present invention relates to an image recording function of a digital camera, and more specifically to a method of efficiently using a recording medium for a digital camera having a limited memory capacity.
2. Description of the Related Art
For a digital camera which records photographed images as digital data in its memory, the number of photographs which can be recorded depends on the capacity of the memory. Specifically, in the case where a built-in memory of a digital camera becomes full, subsequent photographing cannot be carried out without transferring image data in the memory thereof to a personal computer or the like. Therefore, many digital cameras have a function to switch image recording modes according to a purpose of photographing so that their memories can be used as efficiently as possible. More specifically, many cameras have plural kinds of recording modes such as a high quality (high resolution) mode or a compression mode, according to the resolution or necessity of compression of an image.
For digital cameras currently available on the market, such a recording mode needs to be set before photographing, and for image data having been recorded in a memory, the recording mode cannot be changed. However, the purpose of photographing (the usage of images) is not obvious in many cases upon photographing.
For example, in order to print a photographed image, the image needs to be recorded in a high quality (high resolution) mode. However, whether or not an image is printed has not necessarily been decided before photographing the image, and it is often decided after the image is checked to see how it has come out. In such a case, since all images can be candidates for printing, the recording mode should be set to the high quality mode for all images at the time of photographing. In other words, many users record even images only requiring compression-mode quality (which are not printed) in the high quality mode.
As means to solve this problem, Japanese Unexamined Patent Publication No. 64(1989)-81583 discloses a digital camera having a function to read image data having been temporarily recorded in a memory and to re-record the data after compression thereof. When the frame number of an image to be compressed is input from an input circuit of this digital camera, a driving circuit thereof generates a timing signal for reading the image data and gives an instruction to another system. Based on this instruction, the image data are read from the memory card and compressed. The compressed image data are then re-recorded in the memory card. According to this digital camera, the necessity of printing is decided after photographing and re-recording of the image whose printing is not necessary is carried out after compression thereof, for example. In this manner, memory space for further photographing can be saved.
In order to save the memory space, a user has to select some images which may be re-recorded, that is, images whose quality does not cause a problem if it is degraded to some degree. However, in the case where a user wishes to record all images in high quality if possible, for example, it is natural for the user to select the least necessary number of images which will be compressed to compensate for the memory space to be saved. In such a case, the user has to select the images to be compressed, which seem to have comparatively low quality, by comparing each image to the other images recorded in the memory.
More specifically, the user sequentially confirms the images having been recorded and selects candidates for the images to be compressed. After confirmation of all images, if the number of the selected images is smaller than that of the images necessary to save the memory space, the same procedure is repeated. If the former is larger than the latter, the user cancels the selection of some images. In another case, a user has selected one image to be compressed and may wish to cancel the selection after browsing the other images. In other words, it is common for users to select images to be compressed by trial and error.
The digital camera disclosed in the Japanese Unexamined Patent Publication No. 64 (1989)-81583 immediately carries out the compression and re-recording processing once the number of an image to be compressed has been input. Therefore, compression cannot be canceled after the number has been input. As a result, a user needs to select the images to be compressed by trial and error while taking notes for example, and only the frame number of the image having been confirmed as a compression target should be input to the digital camera.
However, the above-described re-recording procedure needs to be carried out hastily in order to save the memory space for subsequent photographing, and it is not desirable for a user to carry out troublesome processing while taking notes, for example. Furthermore, the user has a risk of inputting an erroneous number due to the hasty processing. Therefore, the manner of re-recording where cancellation of an input is not possible is undesirable.
Based on consideration of the above problems, an object of the present invention is to provide a method and a digital camera which allow users to specify a re-recording target by trial and error while carrying out a simple operation and to minimize damage due to an erroneous specification, whereby images are recorded efficiently in a memory.
In order to solve the above problems, the present invention stores, in a memory, a temporary specification of a re-recording target input by a user during the trial and error process, and carries out the re-recording processing collectively by referring to the temporary specification at the time a predetermined operation is carried out.
In other words, an image re-recording method of the present invention records data representing at least one image obtained by photographing in a recording medium;
stores accompanying information received with regard to the data of each image having been recorded, by relating the accompanying information to the image data;
judges, based on the accompanying information, whether or not the data of each image are re-recorded as data having a smaller data size when a predetermined operation is carried out;
sequentially reads image data to be re-recorded from the recording medium, based on the judgment;
carries out conversion processing such that the size of image data becomes smaller than the image data having been read; and
re-records the image data after the conversion in the recording medium.
As the xe2x80x9cconversion processingxe2x80x9d, a resolution conversion to lower the resolution, compression processing such as compression to a JPEG format file, or a combination of the resolution processing and the compression processing are possible, for example. Alternatively, the resolution conversion and the compression processing may have several levels according to the resolution and the compression rates respectively. In this case, the level of the resolution or the compression rate is judged upon the judgment of re-recording necessity, and the conversion processing may be carried out according to the level. xe2x80x9cRe-recordingxe2x80x9d may be carried out by writing the converted data over the original image data. Alternatively, it may be carried out by recording the converted image data in an area different from that of the original data and erasing the original image data from the recording medium thereafter. If the original image data are erased after re-recording, the timing of erasing the original data may be decided by a user. Alternatively, the original data may be erased automatically after a predetermined time has elapsed.
The xe2x80x9caccompanying informationxe2x80x9d may directly specify the necessity of re-recording. Alternatively, the accompanying information may indicate the necessity of printing image data, the content of printing, and the degree of importance of an image, for example. In other words, according to a general judgment criterion, if the information indicates the necessity of printing, re-recording is judged to be unnecessary, since high resolution is necessary for printing. On the contrary, if the information indicates no necessity of printing, re-recording is judged to be necessary. Alternatively, the necessity of re-recording may be judged based on the detailed content of the information regarding printing. For example, when enlargement printing has been specified as a portion of the content of printing, no re-recording occurs. When standard size printing has been specified, re-recording at a comparatively low compression rate is carried out. When no printing has been specified, compression at a comparatively high compression rate is carried out for re-recording. However, the present invention does not limit the judgment criterion to those examples, and the judgment is carried out according to a predefined judgment criterion. xe2x80x9cTo store accompanying information . . . by relating the accompanying information to the image dataxe2x80x9d means insertion of the accompanying information into the header of the image file wherein the image data are recorded. Alternatively, a file describing the relationship between the frame number of an image and the accompanying information thereof may be generated separately from image data files.
The xe2x80x9cpredetermined operationxe2x80x9d may be an operation which requests execution of the re-recording processing directly or indirectly. In other words, the re-recording processing may be carried out by a user""s pressing a re-recording processing execution button or the like provided for that purpose. Alternatively, an operation which has been carried out for another purpose, such as pressing a printing target confirmation button, may be interpreted as a request for the re-recording processing execution.
An image recording apparatus of the present invention re-records an image according to the above method, and comprises:
photographed image recording means for recording data representing at least one image obtained by photographing in a recording medium;
accompanying information recording means for storing accompanying information received with regard to the data of each image having been recorded, by relating the accompanying information to the image data;
re-recording necessity judging means for judging, based on the accompanying information, whether or not the data of each image are re-recorded as data having a smaller data size when a predetermined operation is carried out;
data reading means for reading image data to be re-recorded from the recording medium, based on the judgment;
data converting means for carrying out conversion processing such that the size of image data becomes smaller than the image data having been read; and
re-recording means for re-recording the image data after the conversion in the recording medium.
The image recording method and apparatus of the present invention temporarily store the accompanying information and do not carry out the re-recording processing at the time the accompanying information regarding re-recording target selection is input by a user. When the predetermined operation is carried out, the re-recording processing is executed collectively. In this manner, the user can select the re-recording target as many times as he/she wishes before the predetermined operation is carried out. Therefore, a temporary decision can be input and an erroneous input can be corrected. When the temporary decision becomes the final one, the information has already been input and the re-recording processing is carried out immediately by a simple button operation or the like carried out by the user.
For example, memory space can be saved by re-recording an image which is for display only and has no necessity of printing at a lower resolution to reduce the data size thereof. When printing is necessary, or when the memory space is still insufficient even after re-recording at a lower resolution has been carried out, the memory space can be saved by re-recording image data after compression thereof according to the JPEG format or the like.
Upon re-recording, if an image file is overwritten using the same file name, re-recording can be carried out with certainty and without a problem even when the memory is full. Meanwhile, when the memory has some free space, an image file may be written as another file without being overwritten so that the original image data can be recovered in the case of re-recording due to an erroneous operation.
If the decision as to whether re-recording is carried out or at which resolution or compression rate it is carried out is decided automatically based on the necessity of printing or the print size input by a user, the user can save the memory space by compressing an appropriate image at an appropriate compression level even if the user does not have special knowledge of resolution or compression rates.