The resolution of a digital image can be identified in different ways. If an image is 1000 pixels wide by 1000 pixels long, the resolution is sometimes said to be to be 1000 by 1000. It is also common to refer to the total number of pixels in an image to describe the resolution. Again, for a 1000 by 1000 pixel image, the total number of pixels in the image would be 1000 x 1000=1000000, pixels or 1 mega-pixel.

 

Still another way to describe resolution is by pixels per inch, which is used primarily in the context of printing. This is a measure of how many pixels can be aligned in one linear inch, not how many pixels can fit in an area of one square inch. In one sense, the more pixels per inch that you print the better the image quality will be. In general, the term “pixels per inch” refers to print resolution, while other measures, (like 1024 by 728 pixels) are used in relation to screen or image resolution.

 

The resolution of an image is hinted at indirectly by its file size. A JPEG image that has a size of 25 kilobytes (Kb) will almost certainly have a resolution that is less than a JPEG image with a size of 250 Kb. This is because images with a greater number of pixels require more memory/storage space and therefore have a larger file size.

 

All of these resolution indicators have something in common. In general, bigger is better. The more resolution an image has, the more image information it can contains. This means that image details can be defined better, and that the image can be displayed at a somewhat larger size without having to be re-sampled. It should be noted however, that the type of image format used can make a difference in the image quality, as well as the bit-depth (colour depth) of the image.

 

If your monitor’s screen resolution is set to1024 by 728, you will easily be able to display an image with dimensions smaller than 1024 by 728.

 

 

Here is a 400 by 600 pixel image displayed on a monitor set to a resolution of 1024 by 728.

 

If you try to view an image at its actual size, which is larger than 1024 by 728, you will not be able to see the entire image at once.

 

This is a 2048 by 1536 pixel image displayed on a monitor set to 1024 by 728. Notice that scroll bars are required to view this image at its actual size. This is because the image is just too big for all of it to fit on the monitor at its actual size.

 

 Keep this in mind when you are working on images in Photoshop. Unless your image is zoomed to 100%, you are not seeing the “actual” image. If the image is less than 100% zoom, the image has been downsized (temporarily re-sampled in some way) so it can be viewed in its entirety on your Photoshop canvas.