Auto-merge all layers when dragging *.png file on PSP?

[pstein]

When I drag a *.png file from Windows Explorer onto PSP X2 then always the "Merge all Layer" toolbar icon is enabled.

That means that there are at least 2 layers recognized by PSP.
I don't know why these *.png file contain multiple layers. I doubt that this is the case.
It could be a bug or a wrong preference in PSP too.

So is there a way to automatically merge all layers whenever PSP detects a new *.png file is dragged on it?

Peter

[LeviFiction]

PNGs don't officially support multiple layers. MNG and APNG technically do but PSP is very simple in its PNG support. It wouldn't recognize a MNG and an APNG hides the additional pages behind custom data headers so those would be ignored by PSP.

It's most likely a visual tick in the UI, it's not actually activating Merge All when importing a PNG.

[Forriner]

Sometimes when I drag and drop a PNG into PSP it opens a single "Background" layer. Other PNGs open with a single raster layer, "Raster 1".
I have noticed that PNG files with transparency set, will open as raster 1, and the transparency works in PSP. That could activate the Merge option.
Some PNGs open as raster without apparent transparency, so maybe there are other options in the creating program that cause PSP to open as raster.

[pstein]

So ok, here is an example.

I took this screenshot from Firefox for a certain webpage.

When I drag it "Merge layer" toolbar icon is enabled
why?

I attached the original and the zipped image (to prevent possible forum software download modifications).

sample multiple layers.zip

(209.63 KiB) Downloaded 45 times

[Forriner]

The PNG opens as an image with one Raster layer, not a Background layer. That's how the screenshot was saved so that's how PSP opens it. Merge layer would not be available if it were a Background layer.

[pstein]

How do I find out (independent from PSP) if a *.png contains a Raster Layer?

When I open the same picture in GIMP then nothing special happens.

How do I detect (outside of PSP) if an image is a raster layer?
Does it have e.g. certain byte tokens at files start?

Which (other free) image editors show raster layer is present yes/no?

[LeviFiction]

You're misunderstanding. PNG files do not have a separate raster layer that PSP is opening. What's going on is whether or not the PNG is encoded as an image with full transparency. I want to be clear here, I'm not referring to the image being transparent but whether or not each pixel of the image contains a transparency value. The image itself can be fully opaque but encoded with a transparency value of 100%. If the PNG contains transparency it will open as a Full Raster Layer inside PSP. This is because in PSP only a full raster layer supports transparency. If the PNG does not have a transparency value it will open as a background layer. PSP does this because it assumes you want to keep the transparency that is in the file.

You can change this behavior if it annoys you. File -> Preferences -> File Format Preferences

Choose the PNG tab and change from "Load and Save Transparency to/from Layer Transparency" To "Load and Save Transparency to/from Alpha Channel". Once you do that all PNGs will open as background raster layers. All of them. Every single one. Even ones that you want to be transparent.

[JoeB]

Out of curiosity I have been following this thread. My question is why @pstein cares about this behaviour? In other words, what adverse affect does having the Merge Layers option available have with his/her use of PSP? Just curious....