Hi all, I'm trying to better understand the excellent GDIP UDF by Authenticity So I set myself a simple project to try and create a tonal histogram of an image; I use this in Photoshop a lot. I started with an old example by Toady at the below link (Thank you Toady for getting me started) Unfortunately 'PixelGetColor' seems very slow, so I wanted to see how fast GdipGetPixel would be. So, starting with Toady's example, and using GdipGetPixel function by Vossen and ImageScale and Greyscale