Colour Correction



Colour Correction

Getting back to the colours you remember when scanning slides or negatives has always been a bit of challenge. And my early attempts - using eye alone - were rarely a success.

Checking around the Internet I realised that I was not alone - but also others had tackled and overcome the problem. At least one of these was selling his method - in the form of Photoshop actions - and claiming consistent results. So my challenge was to work out how a standardised script could do better than my guess work.

After thinking about how film is made, processed and made into prints the key seemed to lie in adjusting each of the three primary colour layers separately. And with Photoshop, Photoshop Elements and most other editors that can achieved with a dedicated tool. One that makes the process straight forward.

So to make things as easy as possible here is a worked example ...

Load the image to be edited into Photoshop or similar editor. Then select the Levels option ... something like this


In this example using a colour slide all the image data is compressed to the left. To correct it the idea is to get all the image data just within the black and white sliders under the graph. But we have to do it one colour at a time. I started with Red but the order of adjustment is not critical.


As the white slider is moved to the left the data in the Red layer is stretched. Stop when you reach the start of the image data. - as above. The process is then repeated in the Green and Blue layers. By which point the images should be getting closer to acceptable.


The scanning process does tend to lose contrast - in the days of copying slides by photography high contrast film was used. So I would normally add a bit of contrast to boost the image ... but that is a personal choice.


And that is all you need to get a digital image somewhere near to its equivalent photographic print. Now just save the edited image with a different name and move on to the next one ....

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