![]() ![]() Unfortunately, this process corrects the colours in the film too, reducing their influence and getting them closer to real life. “But what about the colours of the film?” I hear you say. This is good enough for me with just two styles, indoor and outdoor. You then use the white balance module in darktable to ‘auto’ balance the frame, excluding borders. First, choose a representative image for each situation you want a white balance style for. You can do this with the white balance module. You will need to adjust for at least daylight vs indoors. White balance is still a consideration, since the white balance of film is fixed. This process is still necessary even if you have properly calibrated your monitor. This should improve your colour accuracy a lot. Save the resulting style in Darktable so you can reuse in the future with similar film/iso combinations.Unfortunately, I could not get it to work. There is a ‘darktable-chart’ utility that promises to do this automatically. Use the ‘colour checker lut’ module to adjust the target colours to match the source image as best you can.Starting from the lowest ISO, take a photo at each setting you want to calibrate for.Put your camera on a tripod and set it up to take a photo of your colour chart being displayed by your computer.Turn your monitor up to full brightness.Display the macbeth image full screen on your monitor.Download a good macbeth colour chart from the internet.You will have to eyeball what you see on the screen and try to get it to match your physical chart as you see it. The problem with this approach is that you then don’t have a reference to match against. If you have one, then you may want to take a photo of it instead. These calibration charts are very expensive to buy. In the process below, we take a photo of a calibration chart as displayed on your computer monitor. If you are worried about this, then you can still do a full calibration before starting this process. I find it hard to get to a point where the accuracy of the monitor might play a large part in the colour variation. If it is not properly calibrated (mine isn’t) then it will also be corrected, meaning that your colours will be out in relation to how far out your monitor is. This process will compensate for the effect of everything, including your monitor. My process complements ‘proper’ colour calibration and addresses the upstream variations in the analog process. This is the challenge I am attempting to solve here. You still have to get the colours ‘right’ somehow from your negative scan. Colour calibration does not control factors beyond the monitor and printer. So even with proper colour calibration in place, there are factors beyond your control that prevent a fully automated process. Other peoples monitors who are looking at your photos.The development process will never be exactly identical, even when done at a lab.Your lens will affect the colour slightly.Changing ISO will change the colour (pushed or pulled).The film you use, which will have a fixed white balance.Let’s think what can influence the colour… ![]() Just the reference colour targets alone can cost a lot. The equipment needed to do this is expensive. After proper calibration, the colours you see on your monitor will match the colours of your printout. ![]() The ‘proper’ colour calibration process is about making sure that colours on your monitor and on your printer are as accurate to the inputs as possible and do not introduce any alteration. However, if you would like to get your colours closer to reality and wish to reduce the influence of the various factors on the colour, then read on. If that’s what you want, then you’re done with colour correction. Once this is done you are likely to be happy with your image, which will retain all influences on the colour throughout the process, including the influence of the film and your scanning camera. You can then simply use the ‘white balance’ module to automatically adjust the image. It will remove the orange cast and correctly invert the negative image. The Darktable module ‘invert’ goes a long way towards getting accurate colours. These things make getting realistic and ‘correct’ colours quite difficult. Furthermore, your scanning hardware and computer monitor will affect the colour in subtle ways. There is also the problem of ‘what were the colours actually like when I took the photo?’. Early problems that you will encounter are the obvious orange cast to the negatives and also the fixed white balance of film. Digitally processing colour negatives to get an accurate colour reproduction is hard. ![]()
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