Need contrast slider for image

[dreams-togo]

At least for the images in the current test set, the slider for sharpening the image has not been very useful. Perhaps the most useful image enhancement tool would be one that adjusts the contrast, because the digitised microfilm images that we so often work with sometimes have very dark regions in which the handwriting is impossible to read without some adjustment of the contrast; while in other images the handwriting is very faint. We can provide images for testing this.