I think you need to give your program a better name than CHTML - which doesn't really reveal its function. It's too late tonight for me to think of anything better at the moment though.
For the image options box:
I'd make "Image Extension" to "Image Type" and have a drop-list of supported extensions rather than allowing user input. You probably should also put (pixels) by image size so people know what the units are.
And I suspect that you'll add functional browse dialogs for the input/output fields etc?
Re: chtml Testing
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