Transparent PNG output

Is it possible to output a PNG with transparency from MediaBin?

We have a task setup to replace a masked layer within a photoshop doc. We then output to a PNG. Flattening the file seems to remove the transparency, but output to PNG is not possible without flattening (according to error messages received when trying to do so).

Any help is most appreciated.

War-N Harrison

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Migrateduser

I don't think it's the flattener. It's got to be the PNG encoder.

I just made a test with a task containing only the PNG encoder applied on a GIF file with transparency and the background is white.

Folco Banfi

Edited by folcobanfi on 01/25/05 05:50 AM (server time).

Migrateduser

OK, I think I have a solution, but you need to sit down first Smiley Happy

I believe that you can achieve what you're trying to do by using the AGS Encoder.

Your PSD file must be as follows (I have attached my example for reference):
- it must contain a layer set, that contains an empty layer (the one in which you will put your image)
- the mask must be applied on the layer set
- you must go in "Save For Web", select "PNG-8" as the format, check the "Transparency" checkbox, then click on "Done" (NOT "Save")
- save your PSD file

The XML file that will produce the PNG will look something like this (sorry, due to security restrictions here I do not have access to the directory into which these files are to be stored to be used with the AGS Encoder, so all I could do was a test with AGS from the command line on another machine...)
<commands resultOverwrite="true">
<loadContent source="InFile" out="toInsert"/>
<loadContent source="MaskedFile.psd" out="maskFile"/>
<replacePixels in="maskFile" target="/psd/layerSet[@name='Set 1']/layer[@name='Layer 1']" source="toInsert" out="result"/>
<saveContent in="result" name="resultpsd2" appendExtension="true"/>
<saveOptimized in="result" name="OutputFile" appendExtension="true"/> 
</commands>

Folco Banfi

Edited by folcobanfi on 01/25/05 06:19 AM (server time).

WHarrison

Thanx for the tip ... doesn't seem TOO painful! Smiley Happy

I shall give it a try in the next few days.

War-N

Migrateduser

BTW, you may want to remove the <saveContent> element. That was for testing purposes, and I forgot to remove it.

Folco Banfi

lyman

The simple answer is "yes" and the AGS Encoder is in fact the preferred method.

Some of you may want to stop reading now :-) as what follows is more explanation than workaround!

First, the flattener in AGS has two modes. If called without argument it flattens images to a single layer but that layer might still have transparency. However, that is not how Photoshop does it ad the flattener primitive was designed to emulate Photoshop. If you set the mode of the flattener to Photoshop, the transparency is resolved by interpolating a white background that did not used to exist.

The second lesson here is that a gif handles transparency in a much different fashion than PNG or PSD. For gif they designate a transparent "color" among the indexed color values (color map). We do not have support in MediaBin for translating one form of transparency into another (it would be accomplished in a generalized color converter). There are so few file formats that handle transparency the need had not arisen.

There are further details you really don't want to hear that stem from the fact that Photoshop really supports two types of alpha channels, global and layer specific. The difference causes all sorts of special case code.

This is a longwinded way of saying that Folco proposed exactly what I was going to say! In fact, if you have any other image transformations you were going to add to the task you might want to add them to the AGS script instead of appending independent primitives (MediaBin and AGS have considerable overlap in their capabilities and so there will be differences when you use AGS vs MB for, for example, color conversion and scaling).

Sorry to take so long to add to this thread.

Cheers,

Lyman Hurd
MB Server Team

MediaBin Server Team
Interwoven, Inc.

WHarrison

I'm just now getting to this issue and not having much luck.

Wnen using the XML commands referred to above the the following (vague) error is returned:

"Error returned from Altercast"

I can find no log files within the AGS installation directories, so tough to troubleshoot. Can anyone point me to an AGS command reference?

much appreciated.

War-N

Edited by WHarrison on 04/06/05 01:03 PM (server time).

Migrateduser

The AGS (former name Altercast) doc gets installed with the product. C:\program files\adobe\graphics server 2.1\documentation
So, if you have access to the server on which you have AGS, you have the doc.

I would also advise you to try a standalone script first (run it directly against AGS), and once it works try using it through the AGS Encoder primitive.

Folco Banfi

lyman

Reading through the thread I should also state that all AGS scripts for use by MediaBin should have AppendExtension='false'. MediaBin handles extensions itself and doe snot expect it to be done by AGS. A task using the AGS Encoder can (and should) have an extension set for it as a default parameter.

Now, as to the AGS error, unfortunately Adobe choses to map their error stream to stderr which under Windows is not easy to pipe (this would not be a problem in unix!). The best way to find out what the error was, is to write out the AGS command file and explicitly replace InFile and OutFile with sensible choices (i.e., actual filenames) and then invoke AGS (altercast) via the command line. Then, if it does not become obvious, post the error message to this forum.

Thanks,

Lyman Hurd
MediaBin Server Team

MediaBin Server Team
Interwoven, Inc.