The Palm? Zire? 71 handheld with built in camera saves photos in JPEG format. The JPEG format compresses photos to save space on your handheld/expansion card. The Zire 71 handheld displays the number of photos you have room to store in the selected location. This number is an estimate based on memory remaining and currently selected photo resolution (640x480, 320x240, or 160x120).
Due to the nature of JPEG compression, the amount of memory any single photo takes will vary. In a scene with less detail, the size of the photo saved will be smaller. Greater detail in an image will increase the saved photo size.
Below are some approximate photo sizes by resolution selected.
640x480 - 40KB to 60KB
320x240 - 10KB to 27KB
160x120 - 5KB to 10KB