Re: Transparency error when converting a png to bmp

Thanks! So will it be fixed in the next release?

2015-08-17 21:29 GMT+08:00 Bob Friesenhahn <[email protected]>:

> On Mon, 17 Aug 2015, 张铎 wrote:
>
>>
>> Modify coders/bmp.c, change line 1736 from
>> *q++=ScaleQuantumToChar(p->opacity); to
>> *q++=MaxRGB-ScaleQuantumToChar(p->opacity);
>>
>> It fix my problem but I'm not sure whether it is the right approach.
>>
>
> This is likely a more appropriate fix:
>
>             if (bmp_info.bits_per_pixel == 32)
>               *q++==ScaleQuantumToChar(MaxRGB-p->opacity);
>
> since otherwise there will be a problem for anything but the Q8 build.
>
> The alpha channel is inverted in GraphicsMagick from the way it is stored
> in most file formats.
>
> Bob
> --
> Bob Friesenhahn
> [email protected], http://www.simplesystems.org/users/bfriesen/
> GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
>
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