A Potpourri of Image Size Do’s and Don’ts in Photoshop

Here are some tips and tricks to keep in mind when you’re messing around with image size and resolution settings:
-->Use the Unsharp Mask filter when you resample. If you resample your image, either up or down, it is sometimes helpful to apply an Unsharp Mask filter (choose Filter➪Sharpen➪Unsharp Mask). This filter
heightens the contrast between pixels to give the illusion of sharpening or forcing the image more in focus.

-->You can always look without touching. If you don’t want to change the resolution or size of your image, but just get its vital statistics, use the file information box at the bottom of the application window (document window on the Mac). Press Alt (Option on the Mac) and click your mouse button over the file information box. You can see the width, height, channels, and resolution of the document.

-->Don’t change your settings — just use Print with Preview. If you want to leave the size and resolution settings untouched, but need to print your image at a different size, use the Print with Preview command.

-->Try starting out with the proper dimensions. It goes without saying, but I’ll say it anyway. You want to try to enter the proper dimensions and resolution when creating a new document. You don’t want to find yourself in the unfortunate situation of creating your file at 72 ppi, spending hours getting it just perfect and then remembering that you were supposed to prep it for print and really needed it to be 300 ppi. Resampling your image from 72 ppi to 300 ppi is going to make it go from perfect to, well, far less than that. And when scanning an image, make sure that you scan it at a high enough resolution that if you need to enlarge the dimensions, you can do so without changing the pixel dimensions.

-->Don’t use a higher resolution than you need. All you do is create an unnecessarily huge file with a slower print time. In addition, the output device may not be able to reproduce all the detail in the image. In some cases, it may actually make your printout look darker and muddier.

-->Look no further than this blog. Use the handy, dandy table of recommended resolution settings for a variety of output devices.

If you have to downsample your image significantly, for example to 25% of its original size, you get better results if you do several successive 50% downsamples, applying a Unsharp Mask filter on the image in between each image sizing. To remove pixels from an image, follow the steps in the preceding section and change the image settings accordingly.