... today to try again. Although the process I posted last night worked, it was a lot of faff splitting the image, swapping the control template to and fro, and aligning the fixing peg each time. I have successfully got this to work on the full image. The following points appear to be key: 1. use the crop/combine function to remove as much of the image borders and wasted image space as possible. Crop as close to the tracks as possible to make the image as small as possible: 2_250612_170000000.png 2. change the image to 24-bit colour if not already: 2_250559_010000000.png I have for years advised using a reduced colour depth or monochrome images for best results. This is clearly now wrong in the latest versions of the Windows GDI*, and I need to update the notes. It goes against common sense to use massively more memory for full colour unnecessarily, but clearly the GDI is now optimised for this and works much better when manipulating bitmaps in full colour, and when panning and zooming over them. 3 ...