Image size and resolution are stated in different and often confusing units. Here is a quick overview of the commonly used naming systems and labels:
Figure 4-5. Photoshop’s Image Size dialog
File Size depends on the format and compression rate you use to save your image. File size is stated in KB or MB. The image in Figure 4-5 is a compressed TIFF at about 41,4 MB. The same image requires about 15 MB of disk space as a compressed JPEG. File size can vary enormously!
Image Size in Pixels is stated using the height and width of the image as it is captured by the camera. A Nikon D70 produces images measuring 3008 × 2000 pixels ...