Sony DSC-P72 Digital Still Camera Tips and Tricks
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Personal comment: Sony's recent behavior regarding DRM has annoyed me very much and seeing how MemoryStick prizes are several times higher than CompactFlash or SD memory due to the MemoryStick being a proprietary and not widely used format has caused me to recommend not buying Sony products any more.
This is a collection of useful tips and tricks for using Sony DSC P-72 digital camera. Information listed here can not be found in official manuals and had to be found out by test and trial. Most of what is said here should also be valid for other Sony digital camera models. If you can confirm that these tricks also work with other models, please let me know, so I can list the other models here, too.
All experiments with the camera described here were performed under Slackware Linux, but the procedure should be very similar under Windows or any other operating system which supports this model.
Accepted image format
Sometimes it is useful to be able to not only copy files from the camera to a PC's disk, but also to be able to copy files modified or generated using a computer back to the camera (e.g. in order to show them on TV screen). This is a (probably incomplete) list of properties an image file needs to have in order to be readable by the camera:
- Images must have a name of the form
NNNNis replaced by a number with four decimal digits, ranging from 0001 to 9999.
- Images must be stored in folder
dcim/101msdcfon the Memory Stick card (if multiple folders were created by the camera, numbers from 101 up are used).
- Images must be in JPEG format, with baseline (non-progressive) encoding; saving JPG files with Optimize option available in some image editors seems to make them unreadable by the camera.
- Preferably, images should have the same dimensions as the pictures the camera generates (2048x1536, 1632x1224, 1280x960 or 640x480), but this is not necessary — other sizes work too; however, keeping an aspect ratio close to the default 4:3 seems to be a good idea.
- The image's width must be larger than its height. For pictures in portrait mode, EXIF Orientation tag should be used, while the physical image dimensions should be landscape mode (see next paragraph for details).
- No EXIF tags or comments are necessary for the camera to recognize the pictures. The camera itself generates images which have two EXIF IFDs — this is something worth taking into account when changing EXIF info on the PC. Usually, EXIF tags in both IFDs need to be modified in order for all programs to recognize the values correctly.
Rotating images from the camera
There are at least three ways of rotating a JPEG picture:
- Simple rotation — rotating the image in a graphics editor the standard way and saving the result as JPEG; decreases image quality with each operation
- Lossless JPG rotation — available as an option in many graphics editors, can also be performed by programs such as jpegtran
- Modifying the EXIF Orientation tag
Of these, only the last one will generate images which Sony DSC-P72 can decode correctly. The first two methods modify the physical image dimensions, which means that after rotating an image into portrait mode, its width becomes less than its height, which the camera doesn't accept.
Changing EXIF Orientation can be performed with many tools. My favorite is digikam which supports changing images' EXIF Orientation since version 0.7.0. This task can also be accomplished from the command line, using exif. Note that because of the fact that DSC P-72 writes two EXIF IFDs into photographs, both of them need to be modified, so e.g. setting an image's Orientation tag to 6 requires two commands:
exif -t 'Orientation' --ifd 0 --set-value 6 -o image.jpg image.jpg exif -t 'Orientation' --ifd 1 --set-value 6 -o image.jpg image.jpg
The meaning of Orientation values is as follows:
|Value||0th row||0th column|
Note that EXIF Orientation is also used for displaying the thumbnail stored in the image, so changing orientation will automatically make the thumbnail appear rotated correctly. Depending on the software used, other operations (including lossless rotation) may or may not modify the thumbnail to reflect changes made to the "large" image. This way, one can end up with an image, whose thumbnail doesn't resemble the "large" image at all — which may lead to some pretty confusing effects. For example, if one uses jpegtran to losslessly rotate an JPG image, the thumbnail is not altered. As a result, the image may appear rotated correctly when viewed with an image viewer (which uses the "large" image), but incorrectly rotated in the file manager (e.g. konqueror), which uses the thumbnail for display.
Changing the internal picture counter
DSC-P72 maintains an internal counter, which increases with each image shot
and which is used for naming files according to the
convention. It is possible to modify the value stored inside this counter by
placing an appropriately named image file on the flash memory card.
Suppose the last image shot was number M. The internal counter now stores M+1 as the number to be used for the next shot. One can increase this counter by placing an image with number P in the name, where P > M, on the Memory Stick card and turning the camera on. The next image shot will be numbered P+1.
In order to decrease the counter, a trick is necessary. When the counter reaches 9999, it wraps around by going to 0001 again. Thus, one can decrease the value stored in the counter by first setting the counter to 9999 (by the means described in previous paragraph), taking one random shot (which causes the counter to change to 0001), and then increasing the counter to the desired value (the same way as before).