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quality optimisation - photos

The examples I've shown here were taken with a fairly cheap digital camera, but the tips should also help with photos you've taken with a regular camera and scanned in. As mentioned before, you're better off to start with a good quality image. But if you have a photo you want to use that has some existing problems, you may be able to improve it digitally.

The first photo of jellyfish on the right is straight from the camera, taken through glass at an Oceanarium. Digital cameras don't work very well at low light levels, so the quality of the pic wasn't brilliant - the dark areas, as you can see in the detailed closeup, show the characteristic signs of jpeg overcompression - this is what's known as "lossiness". To hide this, I've increased the contrast. Once reduced down to an appropriate size to fit here, the lossiness that was a problem in the original picture is less obvious. It's not a huge improvement, but it only took half a minute.

With the second jellyfish example, I've increased the contrast and also the colour saturation. Again, a minor improvement, but very quick and easy.

For a more typical example of what you can do with a photo, I've used a party snap which had some technical problems:

This involved a little more work than the jellyfish ones. Firstly, I cropped the original to get rid of some of the background. Then, I increased the contrast and dropped the brightness, to get rid of the white haze caused by the flaring of an overhead light. Gamma correction can also be used for this sort of manipulation - try both and see which gives the best improvement for your picture.

The picture then looked bit too red. This can be fixed by adjusting either the RGB or colour saturation - by trying both incrementally, I got it to a point I was happy with.

I then reduced the size to suit my page and sharpened the image. I think it looks quite a bit better than when I started.

If you want to convert an image from colour to black and white, it usually looks better if you increase the contrast quite a bit before converting it to greyscale.