Question about Sony DSC-T7 Digital Camera
Hi - I'm a little confused about the resolution of my photos. I have a 5 MegaPixel Sony DSC-T7. I believe I have everything on the highest setting possible so my images are 2592x1944. The photos are all about 2.2MB. Is this the highest resolution possible? When I open them in Adobe, the DPI says only 76 DPI. And when I print sometimes photos are not as sharp as I would expect. Some photos are out of focus - I believe this is a function of having to hold the camera very still when shooting. How do I get my photos above 200 DPI? Thank you very much for any feedback. Franco
Posted by Anonymous on
It is important to note that the resoution indicator in a camera file is arbitrary and measngless. It tells us nothing about the resultion (or resolution potential) of the image. The only property of the camera image that tells us its reolution (or resolution pitential) is its pixel dimensions. A resolution value in pixels/inch (often spoken of as "DPI" would only be meaningful if the image were intended to represent a certain "inch size" image, not so of a camera image. The image only takes on a resolution in pixels/inch when we commit to print it or display it on-screen at a ceratin physical size. The only impact of the resolution indicator in the camera file is on the "inch size" reported for the image by an image editor. This is also arbitrary and meaningless. In your case (with the resolution indicator at 76 px/in - my guess is that actually it is 72 px/in), the editor would report that the size of your images was 43.1" x 25.6". What does that mean? Well, it only means that if you printed the image at that size, it would have a physical resolution of 76 px/in. The way you can give your 2592 px x1944 px images a physical resolution of over 200 px/in is to print them at a size of smaller than 13' x 9.75". By the way, it is common for camera files to report a resolution of 72 px/in. The specification for the type of JPG file we use today prescribes that if the real physical resolution value "is not available" (read, "is not meanigful"), the arbitrary value 72 px/in should be put in. The reaon for this value is rooted in hiostory, and itself has no meaning today.
Posted on Sep 12, 2005
2.2 MB is the size of the file on your hard disk. Being a .jpg, it is a compressed file. The file size does not reflect the size of the image stored inside the .jpg. Yes, the size sounds about right. It will increase or decrease depending on how much detail there is in the picture. If, for instance, your picture is made up of nothing but uninterrupted blue sky, the disk file will be quite small - as the .jpg does not need to store much information (the more repetitive information, the smaller the file). On the other hand, if your photo consists entirely of nothing but blades of grass, the disk file will be comparatively large. When you see "DPI", that refers to print resolution. So, since you're not printing, but rather, viewing onscreen, Photoshop "assumes" a convenient "screen resolution", as though you printed on the screen (don't ask!). If you look at the other settings, you'll note that Photoshop also thinks your photo is 36" wide!!! You adjust the DPI (or photoshop will) when you print. Till then, it doesn't mean much. Let me give you an idea of your image's possible DPIs. Assume you really want to print a 36" photo: 2592/36" = 72 DPI If you make the picture 12" wide: 2592/12" = 216DPI At 10": 2592/10" = 259.2 DPI At 8" 2592/8" = 324 DPI How do you get my photos above 200 DPI? By printing the picture small enough, less than 12.96" on the wider side. See calculations above. The resolution at which you shot the image (2592X1944), will not cause blurriness. As for the cause? There could be any number. Was the subject moving? Were you? Did you shake the camera while shooting? Is your shutter speed too slow? Should you have been using flash? Is the camera autofocusing correctly? Are you waiting for the autofocus to lock before pushing the shutter the rest of the way? Etc. Hope this helps somewhat...
Posted on Sep 12, 2005
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The screen resolution of the Camera cannot be changed. The option in the Camera is to change the Image size which will increase the MegaPixel rate of the Camera. This can also be called as resolution. This can be changed by touching the Image Size icon displayed on the Camera screen. The settings available for Still Image Settings and Movie Image Settings in the DSCT70 Camera are given in the image given below:
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