Is it possible to capture image from computer with Canon EOS camera and save it to computer? Can the EOS utility used for this?
I want to use my own software (written in Java) to control the camera from the computer and capture images.
As A F said, it's possible to use Canon EDSDK and it's Java wrapper - https://github.com/kritzikratzi/edsdk4j/wiki. It works like a charm.
It is possible. Technically they call it "Tethering Capture" from computer. For example Photoshop Lightroom supports some of EOS cameras for tethering. Please see: http://helpx.adobe.com/lightroom/kb/tethered-camera-support-lightroom-4.html
The "EOS Utility software" does also support tethering/remote shooting. From the menu, choose “Camera settings/Remote shooting”. Please see the following link for further information: http://www.beyondmegapixels.com/2011/02/tethered-shooting-with-a-canon-dslr/
If you are asking can the computer control an EOS camera and take pictures without a photographer's interaction the answer is Yes. There are some limits to what you may do via EOS Utility, the primary one being that you can't change the focal length of a zoom lens without physically moving the zoom ring (or the push/pull barrel) on the lens. You can adjust focus, aperture, ISO, shutter speed, WB, and many other parameters via the tethered interface. You can also set the program up to automatically take time lapse shots at specific intervals. If you plan on continuous shots for more than a couple of hours, you need to use an external power supply or the camera will only shoot until the battery is depleted. You also need to insure adequate space on either the camera's memory card or the computer's disk and be sure to specify the correct location to save the files.
If you are asking can the computer be used for the camera to take a picture of itself being shown on the screen of the computer the answer is, "Not without a mirror as well." You would still need to either turn off the LCD screen on the back of the camera or risk optical feedback in the image.
Yes, it is possible to hook up to the camera and capture images outside of EOS Utility. This can be seen in multiple programs available for Android and iOS which do specifically this. As far as how to write a program to do that, that's unfortunately a programing question, not a photography one and is off topic for Photography. You'd probably have better luck on StackOverflow.