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PMView Pro Forums _ PMView - OS/2 Technical Support _ PNG transparency and Internet Explorer

Posted by: Per Johansson May 1 2003, 04:44 PM

As many people know, Internet Explorer for Windows has limited support for transparency in PNG images. However, it should support 1-bit transparency, for instance you can declare one colour in the colourmap as transparent.
I have a two-colour (black and white) image of which I would like to have the white part transparent. The colour palette shows two colours only, first white and then black.When saving, I select transparency and index 0. It does not become transparent. However, when I try various conversions and end up with a 12-colour palette, transparency works at index 0 for some reason. The image looks bad though.
PMView apparently takes away unnecessary colours from the palette when saving, so converting to 256 colours, all black and white, won't work.
I'm aware that the fault is with IE's bad rendering, but is there any way to work around this?

Posted by: Per A Johansson Jun 1 2003, 05:24 AM

QUOTE (Guest)
As many people know, Internet Explorer for Windows has limited support for transparency in PNG images. However, it should support 1-bit transparency, for instance you can declare one colour in the colourmap as transparent.
I have a two-colour (black and white) image of which I would like to have the white part transparent. The colour palette shows two colours only, first white and then black.When saving, I select transparency and index 0. It does not become transparent. However, when I try various conversions and end up with a 12-colour palette, transparency works at index 0 for some reason. The image looks bad though.
PMView apparently takes away unnecessary colours from the palette when saving, so converting to 256 colours, all black and white, won't work.
I'm aware that the fault is with IE's bad rendering, but is there any way to work around this?

Replying to myself.

This is strange, but I found that as long as the palette contains grayscale only, no matter if there are just two or more colours, Internet Explorer doesn't give you a transparent background. However, if one colour is changed to "not grayscale", for example change white from 255, 255, 255 to 254, 255, 255, the background gets transparent!

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