Can't get colorpalette from some images

[Piotrekk]

Hi

I am trying to get color palette of image and change it:

Image tmpImg = pictureBox1.Image;
// Here tmpImg.Palette sometimes has 0 entries and sometimes has some
entries

However when i debug it i can see that Palette has zero entries for
some images
Does anyone of you know what could be the problem?

Iam trying to get color palette of:

http://mion.elka.pw.edu.pl/~pkolodzi/1.jpg

and change it to:

http://mion.elka.pw.edu.pl/~pkolodzi/2.bmp

On the above example:
Iam able to get color palette of the BMP file here - and unable for
JPG. In different example i CAN get palette of JPG and cant - BMP.

Thanks
PK

 

[Peter Duniho]

I am trying to get color palette of image and change it:

Image tmpImg = pictureBox1.Image;
// Here tmpImg.Palette sometimes has 0 entries and sometimes has some
entries

Not all images have a palette. Only images with indexed pixels values
will. Images with a pixel format where the pixel data is itself the
color information, rather than being index to a table of color
information, will not have a palette.

What palette, for example, should be returned for a 24-bit RGB image?
Should you get a palette with 16 million entries? That's a pretty big
palette.

Pete

 

[Piotrekk]

Not all images have a palette. Only images with indexed pixels values
will. Images with a pixel format where the pixel data is itself the
color information, rather than being index to a table of color
information, will not have a palette.

What palette, for example, should be returned for a 24-bit RGB image?
Should you get a palette with 16 million entries? That's a pretty big
palette.

Pete

Thanks.