Forum: Photoshop


Subject: Format question

bonestructure opened this issue on Apr 27, 2004 ยท 8 posts


bonestructure posted Tue, 27 April 2004 at 1:22 PM

I have several files in .png format. They're intended as textures with opacity maps that are in the alpha channel. Does Pshop handle .png format? If so, how do I extract the alpha channel to get the opacity maps. I need to seperate them into a texture map and an opacity map. I've never dealt with .png files before, don't even know what the heck they are.

Talent is God's gift to you. Using it is your gift to God.


LeFrog posted Tue, 27 April 2004 at 2:25 PM

Well basically png can be thought of as advanced gif images, gif images are limited to the 256 colors as opposed to png where you can have much more of a color gamut. I do not think however that png's can store alpha channel information (but then i rarely use them)i usually use tiff images instead. So the answer is Photoshop does support png but i do not believe it supports alpha channel info.


Hoofdcommissaris posted Tue, 27 April 2004 at 3:14 PM

Stop! .png is actually much more than some kind of gif format. Actually it could well be the internet file format of the future, because it supports 256 shades of grey in alpha. The result is that, for instance, an image on a webpage can be partially transparant and have a transparant soft shadow. Flash can use png images and the best part is, there are two kind of them, the one that resembles .gif (256 color) BUT the other one can have all the colors and transparancy you want AND it is lossless! No artefacts! When you open a .png file, it will be transparant in Photoshop. So that is a good start. When you option-click on the layer (I think it is the same on PC, otherwise use the whatever-key/click combination that makes a selection based on the transparancy of the layer you are in), make a new layer and fill the selection with black. Throw away the layer containing the original image, flatten and save under a different name. Sounds like something you can automate, doesn't it? option-clicking is absolutely necessairy, the magic wand (which I honestly NEVER use) doesn't do half-transparant selection, nor does it select transparant parts inside the layer. The .png format is read by newer browsers as well, but not enough to use a lot on the web. The negative side of doing things with them .png files is that they are rather small, most of the time. So zooming in on parts you texture with them will usually result in blocky textures. The larger the better!


Hoofdcommissaris posted Tue, 27 April 2004 at 3:14 PM

Stop! .png is actually much more than some kind of gif format. Actually it could well be the internet file format of the future, because it supports 256 shades of grey in alpha. The result is that, for instance, an image on a webpage can be partially transparant and have a transparant soft shadow. Flash can use png images and the best part is, there are two kind of them, the one that resembles .gif (256 color) BUT the other one can have all the colors and transparancy you want AND it is lossless! No artefacts! When you open a .png file, it will be transparant in Photoshop. So that is a good start. When you option-click on the layer (I think it is the same on PC, otherwise use the whatever-key/click combination that makes a selection based on the transparancy of the layer you are in), make a new layer and fill the selection with black. Throw away the layer containing the original image, flatten and save under a different name. Sounds like something you can automate, doesn't it? option-clicking is absolutely necessairy, the magic wand (which I honestly NEVER use) doesn't do half-transparant selection, nor does it select transparant parts inside the layer. The .png format is read by newer browsers as well, but not enough to use a lot on the web. The negative side of doing things with them .png files is that they are rather small, most of the time. So zooming in on parts you texture with them will usually result in blocky textures. The larger the better!


Hoofdcommissaris posted Tue, 27 April 2004 at 3:15 PM

And I will say that two times to make it clear! ;-)


bonestructure posted Tue, 27 April 2004 at 3:22 PM

These aren't actually small images, they range from 60 to 90 K on download. It's just, I need to save them as the testure image and the black and white opacity map image, which is in the alpha channel.

Talent is God's gift to you. Using it is your gift to God.


Hoofdcommissaris posted Tue, 27 April 2004 at 3:24 PM

I hope I made clear how you can do that above (twice, because I thought nothing was happening...)


bonestructure posted Tue, 27 April 2004 at 3:31 PM

well, I think I understand the process. I hope I do. These files would help me a lot, and I'd hate to have to make my own opacity maps of them lol.

Talent is God's gift to you. Using it is your gift to God.