Malfunctioning History brush

Trying to follow one of Dr Brown's CS2 tutorials, I find that when using my history brush, a click on the mouse does not alter the picture, but merely adds one more line in the history popout that says 'history brush'. After 50 or 60 new lines I figured it wasn't working. I asked about this on a PS forum and got no answers. It has to be a simple setting somewhere - can anybody help?

Thanks - Chuck B

Did you specify correctly where the history comes from? For example: if you click the last history entry, then the history brush will indeed not change anything because it doesn't go back in history.

Johan, no matter what I do, the history brush simply has no effect on the image. I should be able to select the brush, select a mode (such as 'multiply'), and paint away. But, nothing happens except to add one more line to the history window. I am following Dr Brown's tutorial on "History Painting 101" and I can add a levels layer, specify 'multiply' for the layer, and see the effect on the whole image. But, and I just did this again, following his instructions for the brush alone I get nothing.

When you say, 'specify correctly where the history comes from,' could you describe exactly what you mean? For instance, if I have the original locked background later, and add a levels layer, the history brush is forbidden. The tutorial has only one layer and the only selection he makes is to the brush parameters themselves.

-- Chuck

Hi Chuck,

I've never used it before, but the following is a simple test I've devised, it works for me....

Simple test for history brush in cs2

1 - open an image
2 - copy the layer. You now have 'background' and 'background copy' in the layers window
3 - select Layer, (alt L menu item) then image-adjustments-invert to dramatically alter the 'Background Layer' colours.... (or Ctrl i)
4 - select history brush tool - ensure opacity, flow set to 100% set to normal, 30 pixel size, say.
5 - go to the history window - 3 items are there - 'Open', 'Duplicate Layer' , 'Invert'
6 - select 'Duplicate Layer', then left click in its lh check box - it then shows a brush symbol
7 - select 'Background Copy' layer (it should still be selected)
8 - paint away

If you see nothing happening, then I think you have a problem.
If you get the original image appearing with the brush strokes, then experiment, its working fine.

Best wishes,

Ray

Chuck Bragg said:

Johan, no matter what I do, the history brush simply has no effect on the image. I should be able to select the brush, select a mode (such as 'multiply'), and paint away.

Click to expand...

No, not like that you shouldn't. Before you can use the history brush, you have the select a history state that acts as the 'sample' for the brush. You do that by clicking in the small box on the left of the history state. Ray's example is a good one. Try it to see if it works and to see if you understand now how the history brush works.

Johan & Ray - well, with Ray's methodology the brush does work. I can leave out the 'invert image' step and it still works. The difference between Ray and Dr Brown is the addition of the duplicate layer. Dr Brown did not use one, and the brush didn't work for me. Previously, when I added a *levels* layer, *not* a copy/duplicate, the brush was disallowed (as opposed to being allowed, but not working). Now everything is working. Thanks to you both!

-- Chuck B

Always think how the history brush would have to do its work, then you'll understand why certain things don't work. If you add a levels layer, and you try to use the history brush on that step, what would be the result? A layer with a whole in it, because at the place where you painted there is no layer? There are many things you simply cannot paint back with the history brush, because these things are 'all or nothing'. You can't paint back a conversion from 16 bits to 8 bits, for example. Same with a conversion from one profile to another. Or the addition of a layer. If you think about it, that is completely logical.

JohanElzenga said:

Always think how the history brush would have to do its work, then you'll understand why certain things don't work. If you add a levels layer, and you try to use the history brush on that step, what would be the result? A layer with a whole in it, because at the place where you painted there is no layer? There are many things you simply cannot paint back with the history brush, because these things are 'all or nothing'. You can't paint back a conversion from 16 bits to 8 bits, for example. Same with a conversion from one profile to another. Or the addition of a layer. If you think about it, that is completely logical.

Click to expand...

Johan,

I don't see why one can't do these things!

It is to me, counterintuitive.

Asher

Just think about it. Suppose you would partially paint back a conversion from 16 bits to 8 bits. That means that you would end up with an image where half the pixels are 16 bits (the ones you painted back) and half the pixels are still 8 bits. That simply doesn't exist, and even if it could exist in theory, it's not supported by Photoshop and it's not supported by any of the existing file formats.

Same for layers. You either have a layer, or you don't. You can't have 0.2 layer. Same for color profiles. An image is either sRGB or AdobeRGB, it can't be 0.25 sRGB and 0.75 AdobeRGB. Things like that are simply not possible in Photoshop or any other graphics program, and they are not supported in any file format.

That's why it's logical that these things are also not possible to create using the History Brush.