Convert color JPG to grayscale with GD

[martijnw]

I've been struggling with this problem for a few days now. I want to upload truecolor JPG photo to the server, and then convert it to a grayscale JPG with the GD-library.

Here's what I already tried:

• convert the truecolor image to a palette image, and then use the imagecopymergegray function (no success)

• convert the truecolor image to a pallette image, then use a routine that evaluates the color of each pixel and calculating the grayscale value for that color and create a new image with the grayscale pixels (no success)

I would like to use the truecolor images instead of 'degraded' dithered palette images. Is there a way of doing that (maybe with another graphics-library)?

Can anyone please help me out?

[[deleted]]

Have you checked if Imagsamagic or some other free utility can do it? might be simpler than GD...

[toma42]

Yea, it can...check this:
http://www.imagemagick.org/www/convert.html

[Anon]

I want to know how to convert this too. If anybody have the solution, please mail to me .

Martijn wrote:

I've been struggling with this problem for a few days now. I want to upload truecolor JPG photo to the server, and then convert it to a grayscale JPG with the GD-library.

Here's what I already tried:

• convert the truecolor image to a palette image, and then use the imagecopymergegray function (no success)

• convert the truecolor image to a pallette image, then use a routine that evaluates the color of each pixel and calculating the grayscale value for that color and create a new image with the grayscale pixels (no success)

I would like to use the truecolor images instead of 'degraded' dithered palette images. Is there a way of doing that (maybe with another graphics-library)?

Can anyone please help me out?