Issue with Merge Down

[BoltBait]

OK, I ran into an interesting issue with the Merge Down function.

Steps to reproduce:

1) Open a graphic

2) Load a new (smaller) graphic on a new layer

3) Duplicate that new layer and make the top layer invisible

4) In the middle layer, select the new graphic and press to fill it with black

5) Move selection 8 pixels down and 8 pixels to the right (using the arrows, and the move pixels tool)

6) Select the entire layer and Gaussian Blur (8). This should make a nice drop shadow.

7) Change the layer properties to 128 transparency

8) Make the top layer visible

9) Merge down the top layer into the shadow layer

Notice how the graphic no longer looks the same!

BTW, Image Flatten works properly. I think when merging onto a layer, every pixel on that layer must be adjusted based on the trasnparency setting of that layer BEFORE the new pixels are merged onto that layer.

All I can say is, you better not remove this functionality from the final build just because it has an issue or two!!!

[BoltBait]

BTW, when a layer has a blending mode other than Normal, the results of a Merge Down are similarly unpredictable.

All I can say is, Rick, you better not remove this functionality from the final build just because it has an issue or two!!!

[Rick Brewster]

Yeah that happens because the shadow layer is set to 128 transparency.

"Merge Down" is not intended to produce an image that renders equivalent to the original. Even Photoshop doesn't do that. It's just not really mathematically possible.

[BoltBait]

I can see it not being possible for blending modes other than "normal", but I think it would be possible to compensate for layer transparency.

[Rick Brewster]

Well it's "merge down", ... you're asking me to change the layer properties of the destination layer in this case.

[TinSoldier]

I read your first post and I believed that I had a solution. Instead of merging down the top layer onto the shadow layer, why not merge the shadow layer down to the background?

I tested it and it worked:

I didn't have the same images as you did so I had to make do. Note: I feathered both the shadow and the inset image before flattening them and I set the shadow to 192 transparency instead of 128 because of the darkness of the pictures.

Edit: I didn't try different blending modes...

[BoltBait]

That is correct. It works fine in that direction. However, I wanted to merge the inset picture with its shadow and leave the background graphic alone.

I think I will need to make my drop shadows differently, that is all. Maybe I'll use that drop shadow plugin.

[MadJik]

Flattening the three images as once is perfect instead merging down two layers...

[barkbark00]

Another solution is merging the shadow layer down onto a blank layer with 255 transparency. I've tried it and it works. Its basically the same as TinSoliders solution but you don't end up with unwanted stuff on your background or any other necessary layers.

If there was a "Merge Up" option, that would work fine, cuz then it would take image from the shadow layer with its lowered transparency and keep the layer transparency of the top layer while combining both.

IMO I think BoltBait's Plugin works nicely. It makes the layer transparency concept a little more intuitive. But, logically, the way the Layer options work now is correct.

[BoltBait]

barkbark00, that is a great idea.

Create a blank layer under the shadow layer and merge the shadow layer down to that layer before merging the picture layer down with its shadow.

That works perfectly. Nice job.

Of course, if I'd thought of that, we wouldn't have the Transparency Adjustment plugin...