Re: [Boost-users] [GIL] Premultiplications when using color_convert

Subject: Re: [Boost-users] [GIL] Premultiplications when using color_convert
From: Lubomir Bourdev (lbourdev_at_[hidden])
Date: 2010-04-12 15:43:43

Hi Eloi,

One solution is to define your own color space “rgba_premultiplied_t” and provide color conversion functions from/to it.

In your example, did you mean to use rgba32f_pixel_t ?  Also wouldn’t p1[3]=0.0f set the alpha to zero? In this case the color is fully transparent. I am not sure what you would expect...

Lubomir

On 4/12/10 6:38 AM, "Eloi Du Bois" <eloi.du.bois_at_[hidden]> wrote:

Hi all,

I am working on rgba32f view that have alpha values of 0.
I need to apply a color_convert but it drops the values because of the 0 alpha valued.
How can I disable alpha premultiplication ?
If impossible, it should be a good idea to give a choice on copy_and_convert & color_convert.

code sample:
rgb32f_pixel p1, p2;
p1[0] = 1.0f;
p1[3] = 0.0f;
color_convert(p1, p2);
assert(p1[0] == p2[0]);

Thank you by advance,
Eloi Du Bois.