The History Tool In Photoshop

How much use do you make of the history tool in Photoshop?

The history tool can be used serveral ways. First, you might add an effect to one part of an image only that is normally global - that is to say it applies to the entire image - eg. sharpening, blurring, ehnancing or whatever. You have two choices. You can apply the effect then remove it from selected areas by clicking on the history pallete to set the history brush, then paint into the areas you want to undo or tone down the effect just applied. You can also do the opposite. Select the last change as the history marker then highlight the prev. step as being the current one. Now when you paint with the history brush, you apply the effect only to where you paint.

Examples of where this can be helpful is sharpening. You might want it everywhere but over the water or clouds.

I save my burning and dodging for after I have done all my curves work. I normally do this by duplicating the image a second layer, apply all the dodging and burning, then turn it on and off to see if I have improved the image. I can add a mask to the top image layer and paint black in it to undo or tone down the dodging and burning in a selected area. I could have used the history brush though to do the same thing - so long as the change is within the memory of the history - I have my computer set at 20 history steps. In theory you could set this at 200 steps but the amount of hard disk space and or memory taken up becomes nothing short of absurd - every local change to an image increases storage requirements by the size of the image so you could theoretically end up using 200 times the memory size of the original image file.

The history brush can be used when you have done 10 things since you did what you want to undo - rather than undo 10 times and have to redo all the good work you did after the thing you want changed, you can apply the history state to this one step, paint it locally and you are done. Of course, this only works if the subsequent steps didn't drastically change the area you applied the history brush to. It wouldn't work if you were to do a global colour balance adjustment which renders the history painted area a different colour from the rest of the image. More often though, the changes are not such that the small area painted 10 steps backwards are significant.