GIMP Version: 2.8.14
Operating System: Windows
GIMP Experience: New User

List any relevant plug-ins or scripts:
Batch Image Manipulation

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Hi

So, title says it all, basically, I need to do Layer->Transparency->Remove Alpha Channel from bmps for over thousand times and I was wondering if there is anyway it could be done faster?

I'm desperate, I searched for it in the internet like mad, I even tried writing a script (which, I completely don't know how to do) and I'm at loss. Changing to format not supporting transparency and back again doesn't help. Nothing helps but this one option. I mean, I could index the colours to 255/256, but it really worsens the quality of the image, and the "Remove Alpha Channel" leaves the quality untouched, while the bitrate from 32 to 24. Please, please help me, please

And thank You in advance

To process images in bulk, the best tool is ImageMagick, and even though there is no "color to alpha" operator, it can be done:

https://stackoverflow.com/questions/264 ... e-the-gimp

@Sei

Want something with a GUI - try XnConvert - http://www.xnview.com/en/xnconvert/

All you need is add one action change color depth and set 24 bits as the depth.

example http://imgur.com/swqLN9J

A big Thank You to you both for such a quick response.

While I'm sure ofnut's idea would work alright if done properly, I used XnConvert and it works Quality stayed the same, but it (finally!) changed to 24bit.
Thank You sooo much

Alpha channel should be 32-bit, not 24.
8 for red, 8 for green, 8 blue and 8 for alpha.

True, but read the first post/subject title again

I read it, but don't understand the logic behind it.....

Anyway ffmpeg can do it in a batch mode to convert all 32-bit bmp images in a folder into 24-bit png images or whatever. Assuming the OP uses Windows, this batch script should work:

What is that saying, which starts Ours is not to reason why...



Well the OP says he uses Windows and certainly you could do that with ffmpeg, but why? Ofnuts gave the best option with ImageMagick which could be as simple as:



Which will convert a whole directory full of .bmp images in place. Dangerous command is mogrify

Not everyone, especially Windows users are comfortable with using a terminal, hence a GUI option. I would have suggested BIMP as a Gimp plugin but the BIMP .bmp export function has no colour depth options.

edit: Not quite true, it is possible with BIMP, I forgot the obvious, flatten the image, not something I normally do bad practice. That comes under Other Gimp Procedure = gimp-image-flatten then use the BIMP Change Format and select bmp. Nicely keeps semi-transparent pixels as shaded colour. Of course it is not 24 bit, still has an alpha channel but no transparent area.

I'm not familiar with ImageMagic commands and never used it. I am familiar with ffmpeg and use it often. There is very little ffmpeg can't do and it does it all very well. It is my go-to program for batch converting and much more. Anyway, it's just another option.