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bsabiston

Joined: 20 May 2010
Posts: 3



PostPosted: Thu May 20, 2010 11:17 am    Post subject: BMP with alpha Reply with quote

Hi, I am trying to create a BMP image with alpha. I'm using CS3 and it has options in the save dialog for saving 32-bit BMPs. The 'advanced options' even allow you to select between XRGB and ARGB, thought I don't know what that means.

However when I save the image and load it back in, the formerly-transparent areas of my image are now white. Is it not possible to save BMP's with alpha? I have seen several reports online of people saying that it works. What do I need to do?

Thanks
Bob
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Auieos

Joined: 29 Jan 2010
Posts: 2019



PostPosted: Thu May 20, 2010 7:00 pm    Post subject: Reply with quote

found your question on a dead thread...
http://www.photoshopforums.com/transparent-bmp-s-vt149.html

I'm with you as far as there seems to be a whole lot of people who claim they can do it. When i had a look there was a strong theme around icon & cursor creation so if that's what your after these may help.
http://www.telegraphics.com.au/svn/icoformat/trunk/dist/README.html

Now u have me intrigued. :)
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bsabiston

Joined: 20 May 2010
Posts: 3



PostPosted: Thu May 20, 2010 8:52 pm    Post subject: Reply with quote

Well, I haven't discovered a Photoshop solution, but GIMP does it. With GIMP you do not even have to use the bitmapv4header, you can just use the regular BMP header and specify 32 bits. Doesn't help for Photoshop use but still it's the best thing I have found so far...
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Auieos

Joined: 29 Jan 2010
Posts: 2019



PostPosted: Fri May 21, 2010 10:13 pm    Post subject: Reply with quote

yeah good that you got your problem solved, go freeware!

In case ur curious, I had a bit more of a look, the info seemed to point towards indexed colour.

Quote:
To make a transparent bitmap you must make sure that the bitmap has been converted to Indexed 256 colour. 24bit Bitmaps will not make a transparent image. Make sure that pixel (0,0) in the top left most part of the picture has the colour you want to be transparent.

If you have a background colour that you do not want to be transparent put another colour at pixel (0,0), preferably 1 that doesn't appear in the rest of the image. Some image editors allow you to add a colour to the palette if needed.

In some cases setting colour 0 in the colour index also can help.


found a Tutorial too

http://football-freaks.com/forums/index.php?s=c641fdf28fa03ad8067f5d2071ef1c1b&showtopic=24851&st=0&#entry287220
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bsabiston

Joined: 20 May 2010
Posts: 3



PostPosted: Fri May 21, 2010 11:39 pm    Post subject: Reply with quote

yeah, i guess i had heard about indexed color transparency, but I am looking for full 24 bit color with alpha channel, where any pixel can have any level of translucency. you have to have 32 bit color for that.
thanks for looking into it,
bob
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Auieos

Joined: 29 Jan 2010
Posts: 2019



PostPosted: Sat May 22, 2010 6:47 pm    Post subject: Reply with quote

No Problemo
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arthurslice

Joined: 04 Sep 2011
Posts: 2



PostPosted: Sun Sep 04, 2011 3:30 am    Post subject: Reply with quote

What version of Photoshop you are using?




____________________________________
Submit your articles free


Last edited by arthurslice on Tue Sep 20, 2011 4:17 am; edited 1 time in total
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jerryb4417

Joined: 20 Dec 2008
Posts: 710
Location: Oklahoma
PS Version: photoshop cs5
OS: win7 pro 64 bit, i7-3.2g, GTS 450,

PostPosted: Sun Sep 04, 2011 7:45 am    Post subject: Reply with quote

hi authur,
that pretty old thread.... grin..i have done that a few times...

but if the guy is still around... the short answer for him is that the bmp format will not allow for a alfa/transparent channel ...

he needs to save it in either gif or since he wants 24 bit it needs to be in png or tif
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