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Thread: Batch convert PNG loses Alpha channel

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    Question Batch convert PNG loses Alpha channel

    Hi! Long time lurker, but never posting!

    I am encountering a frustrating problem: Using the batch convert option to convert PNG files to grayscale drops the alpha channels of the original PNG files. Doing each manually keeps the alpha channel.

    Am I using the batch convert wrong

    Note: It is an alpha channel, not a transparent color.
    Last edited by jbgrobler; 17.07.2012 at 12:36 AM. Reason: Fix spelling mistakes!

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    Moderator Enterprise User Bhikkhu Pesala's Avatar
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    IrfanView doesn't support Alpha Channels — only single colour palette transparency.

    I don't know about greyscale PNG with alpha transparency, but if you open a 32-bit PNG in IrfanView, and check out the image Info dialogue, you can see that the copy on disk is 32-bit while the copy in memory is 24-bit.
    Last edited by Bhikkhu Pesala; 17.07.2012 at 03:55 AM.

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    I could have sworn I did it manually, but I checked again. It DOES save an alpha channel, but it is completely blank (when using PNGOUT plug-in).

    Oh well, thanks for the reply! Any suggestions on an utility that can batch convert images and keep transparency?

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    Hobby User Sprintdriver's Avatar
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    Quote Originally Posted by jbgrobler View Post
    Oh well, thanks for the reply! Any suggestions on an utility that can batch convert images and keep transparency?
    Hi. What source format does your existing images have?
    If it hurts not to drint, don't waste the bottle then.

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    They are color PNG sources from a professional graphics designer that charges by the hour. However, I need them in smaller grey-scale as well, almost like big thumbnails, and keep their alpha layer.

    Currently I have to do this manually every time I get new or updated images, and it is extremely tedious.

    When IrfanView introduced the ability to view the alpha channel I thought it must support it now, but I was wrong.

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