Thanks a lot. Now I just have to ask how I save the changes? It seems like cairo_image_surface_get_data only returns a copy of the data. I've tried to use the create_for_data function to create a new surface from the data, and save it using write_to_png, but it seems like it creates a few problems for some pixel, that get totally white.. I'm using pycairo, but guess it should be working the same way: surface = cairo.ImageSurface.create_from_png(test.png) buffer = surface.get_data_as_rgba() surface = cairo.ImageSurface.create_for_data (             buffer, cairo.FORMAT_ARGB32,             surface.get_width(), surface.get_height(),             surface.get_stride()) surface.write_to_png("test_out.png") <div> On 11/19/06, Andrew McRae <<a href="mailto:amcrae@employees.org">amcrae@employees.org</a>> wrote:<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> On Sun, 2006-11-19 at 12:57 +0100, Lobais wrote: > Hi, it is possible to get the image data of an image, such that one > would be able to e.g. get red, green and blue from pixel 8 row 4? > > -- > Best Regards, Thomas The easiest way (from what I know) is to use cairo_image_surface_get_data and friends. As long as you know it's a RGB or ARGB format (you can check with cairo_image_surface_get_format), it's going to be a 32 bit pixel element image. Here's a sample code snippet:   unsigned char *data = cairo_image_surface_get_data(surface);   int stride = cairo_image_surface_get_stride(surface);   uint32_t *pixelptr;   ...       pixelptr = (uint32_t *)(data + 4 * stride); // row 4       my_pixel = pixel[8];                        // pixel 8       red = (pixel[8] >> 16) & 0xFF; Cheers, AMc </blockquote> </div> -- Mvh. Thomas