Hello Lubomir, Hailin and the other boosters, I implemented support for more png file types, including palette and grayscale with alpha images. For the implementation I had to add a gray_alpha layout, and extend the color_type metafunction for homogeneous bit_aligned_pixel_* types - packed_pixel is still missing. I tested 1,2 and 4 bit images with http://www.schaik.com/pngsuite/pngsuite_bas_png.html and some images with I also added additional calls to png_packswap to get proper results for 1bit images. Could you review the changes? A svn diff of boost/gil/ is attached to the email. I have a boost svn account, and could add that stuff myself, if you want me to. I could also add more test cases that capture more of the png file types. kind regards Andreas Pokorny