Quick CS3 Experiment

[KevinStecyk]

Can someone please try the following and let me know their results?

Try this as an experiment:

1) Open any file in RGB mode.

2) Image | Duplicate

3) Shift Drag one image to the other. The Shift ensures "pin registration."

4) Use blend mode Difference for the second (top) layer. It should be all black (that is, no difference). Then use Control M for curves on the top layer. Do you see slight differences between the two pictures when you adjust the curves?

[ChrisPerry]

yes. depends on how I tweak it, but color negative is what it reminds me of.

[KevinStecyk]

Hi Chris,

I made an error and now everything makes sense.

It should have read as follows:

Try this as an experiment:

1) Open any file in RGB mode.

2) Image | Duplicate

3) Shift Drag one image to the other. The Shift ensures "pin registration."

4) Use blend mode Difference for the second (top) layer.

5) Flatten the file so that only one, top layer remains, the black layer.

6) Use Control M for curves on the top layer. Do you see slight differences between the two pictures when you adjust the curves? My guess is that now you see no difference. That is, Photoshop does produce identical files.

I just discovered my error. Thank you Chris for helping me.

Best regards,
Kevin

[Noel_Carboni]

No difference here.

Another way to try it is to add a Curves adjustment layer above the layer that is set for Difference mixing, and pull the curves WAY up. This is a great trick, by the way, if you need to edit what's in the deep shadows of an image.

-Noel

[KevinStecyk]

Originally Posted by Noel_Carboni

No difference here.

Another way to try it is to add a Curves adjustment layer above the layer that is set for Difference mixing, and pull the curves WAY up. This is a great trick, by the way, if you need to edit what's in the deep shadows of an image.

My Step 6 (Control M) does the same thing except it doesn't add a layer. You make the adjustment on the layer that you are on rather than adding an adjustment layer.