Hints and Tips

Using the Unsharp Mask in Adobe Photoshop 7

I think it is almost universally accepted that the last thing to do when printing a computer image is to sharpen using the unsharp mask.

When you hit filter on the task bar the drop down list appears and you highlight unsharpen. You should be at 100% size to view the image in the preview box of unsharpen. You can then adjust the three sliders to your satisfaction. The AMOUNT slider determines the amount of sharpening applied to the photo. The RADIUS slider determines how many pixels out from the edge the sharpening will affect. The THRESHOLD slider determines the intensity of sharpening and the lower the number the more intense the sharpening. The THRESHOLD determines how different a pixel must be from the surrounding area before it is considered an edge pixel and sharpened by the filter.

Now comes the interesting part. It is much better to sharpen in Lab Mode. Up to now you have been in RGB mode. Highlight IMAGE on the task bar and then MODE. Then extend the drop down list via the arrow and click on LAB COLOR. You have now separated the channels. Go to WINDOW on the Task Bar and hit CHANNELS and a box will appear with lab, lightness, a and b channels. Highlight the LIGHTNESS channel. NOW go through the unsharpen as you would normally when in RGB mode until you are happy with the result. What you have done is to sharpen only the black and white and avoided colour halos because you are not sharpening the colour channels. Now change back to RGB mode.

Takes quite a time so now for the trick. Before going into lab mode open from the task bar WINDOWS and from the drop down list highlight ACTIONS just under history. Next from the Actions pop down list highlight NEW. Name what you are going to do “my lab 1 sharpening” or whatever you like in the box “name”. Then go to FUNCTION KEY box and choose anyone from F1 to F12. (use f2 for this exercise). Now go ahead and sharpen your picture in lab mode as previously you would have done in RGB mode and all the while Photoshop will be recording what you are doing. Smart! Now in the ACTIONS all your steps taken will be shown and to finish HIT the little square button at the bottom of the palette (first from the left). DONE great work.

NOW open a new photograph and HIT the F2 and the picture will be sharpened automatically in lab mode. You can do this for several different unsharpen procedures using different F numbers so you have batch of different setting you can use at the touch of a key.

Submitted by

Ian Vaughan