Digital photography colour differences

Jakko

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I thought I’d post some proof that, in digital photography, the overall colour of the thing you’re photographing makes a lot of difference to the colour of details, because the whole picture determines what the colours of different parts will be. Compare these two photos:

IMG_4503.jpg
IMG_4507.jpg

It’s the same model, photographed in the same photo booth with the same lighting, using the same iPad, and neither photo has been adjusted in any way. In the photo with the blue background, the model looks green-brown, but with a white background, it looks brown. (For the record: the model is painted brown.) Here’s the result of using the colour eyedropper tool in Photoshop on pretty much the same spot (the upper side of the left front mudguard) on the model in both photos (blue background first, white background second):

Blue background.pngWhite background.png

Short version: if the model in your photo seems to have the wrong colours, try using a different background.
 

Peter Gillson

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Very interesting. I wonder what sort of difference there would be using traditional film.

Peter
 
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It's a real problem. I've found that the best general background colour is a medium blue grey, which is fairly neutral and doesn't overwhelm the camera. My camera has a problem with reds - I suspect it's intended to make flesh colours warmer when taking portraits. I use the Photo function in my computer's (Microsoft 365) picture editing suit to adjust the colouring where necessary.
 

Jakko

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Very interesting. I wonder what sort of difference there would be using traditional film.
The model would be brown with either background. The colour in film depends on chemical reactions caused by light, reflecting from the subject, hitting the film. This means that each individual spot is coloured only by the light that hits it.

With a digital camera, the light from the subject hits a CCD (charge-coupled device), basically a chip containing a grid of tiny light-sensitive sensors that give off electricity when they are illuminated. This is “read” by the camera to decide what colour each pixel in the photo should have. However, this is then processed by software, which makes all kinds of assumptions about what’s in the image and changes colours accordingly.

For example, I first took the photo with the blue background. I then decided to try and adjust my iPad’s white balance by putting a white A4 paper next to the model, tapping on that on the screen (this makes the iPad’s camera app focus where you tap and set exposure based on that point as well). This resulted in a brown, not green, model — but as soon as I removed the paper, the majority of the image was blue again and so the iPad changed the model on the screen to green right away. Put the paper back into shot, and the model was brown. That’s when I decided to put up the white background for the photos instead
 

Tim Marlow

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Hi Jakko
The issue isn’t necessarily the ccd, the built in iPad software is also designed to make JPEG images pop when viewed. It’s one of the reasons SLRs have a RAW (unprocessed) photograph setting because professionals want complete control over image manipulation.
If you took this picture with wet film you would have the same issue because despite what reaction happens at the film interface, the printing process would modify the colours for the same effect...wet film was/is also far more susceptible to variables such as temperature and storage, and different brands reacted differently in various situations so inconsistencies were even worse....
 

Tim Marlow

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Ignore my post, I’ve mostly just repeated what you posted....teach me to read properly won’t it :flushed:
 

Jakko

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If you took this picture with wet film you would have the same issue because despite what reaction happens at the film interface, the printing process would modify the colours for the same effect...
But that’s introducing other variables — to make a fair comparison, you’d have to use methods that avoid those. Take the comparison pictures on the same film, one right after the other, process them exactly the same and at the same time, etc. If you don’t, then yes, the process may have all kinds of unpredictable influence on the photos.
 

Tim Marlow

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True, but in my experience auto printers used to be set on an average face colour setting and just left to run...they certainly weren’t optimised for each picture....I have wet film Native American pictures taken at a pow wow that have faces that are pretty much as white as I am, for example.
Cameras do something similar and tend to average the light and the white balance as well, if you set one on full auto and take shots of a white card, a grey card and a black card they all come out essentially the same because the camera tries to expose them to make them all a mid grey.. auto white balance will do this by adjusting the colour balance based on the dominant tone. In essence though, I think we are saying the same thing. Basically cameras ain’t that bright, so you have to think for them.....
Cheers
Tim
 

Jakko

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I think that sums it up quite nicely. They’re so smart that they act stupid if you know what you want.
 

Tim Marlow

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Mind you Jakko, knowing you have to do it is the easy bit....doing it right is the hard bit LOL
 

Tim Marlow

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Looking back at your original pictures, the allied star on the turret illustrates exactly what is going on. The green example has a blue tinted star and the brown example has a red tinted star....if you applied white balance correction to both pictures they would get much closer together in tone. Incidentally, the white background is also slightly underexposed because the camera has tried to turn it grey....which also illustrates that facet. If you are photographing against a white background it may be worth using a snow setting if you have one?
 

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The other big issue that plays havoc with the colours is the lighting, there is a big difference between an image taken under tungsten lights and midday natural light. And even with natural lighting there are differences between dawn, midday and dusk.
 
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Tim Marlow

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True Dave, colour temperature varies by light source and in natural terms, by the time of day and weather conditions. However in Jakko’s case the same light source was used so colour temperature wasn’t an issue.
 

dave

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True Tim, but I thought I’d throw it in any way as a different reason for the same colour looking different in pics.
 

Tim Marlow

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Thanks Dave, and when you add in colour calibration of monitors, printers etc (or the lack of) we are on a hiding to nothing :tears-of-joy:
 

Jakko

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Looking back at your original pictures, the allied star on the turret illustrates exactly what is going on. The green example has a blue tinted star and the brown example has a red tinted star....
I hadn’t really looked at those, but doing so now: you’re right, the blue especially is very noticeable.

if you applied white balance correction to both pictures they would get much closer together in tone. Incidentally, the white background is also slightly underexposed because the camera has tried to turn it grey....which also illustrates that facet. If you are photographing against a white background it may be worth using a snow setting if you have one?
I don’t think the iPad’s default camera app can do that. Focus and exposure can be set by tapping on the area of the screen you want to it to base those on, but there’s no way I know of to manually set colour balance and similar things. Maybe I should do an experiment with a digital SLR camera and the same setup with the different backgrounds, see what that makes of it both as JPEGs and the RAW files.
 

Jakko

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The other big issue that plays havoc with the colours is the lighting, there is a big difference between an image taken under tungsten lights and midday natural light.
In this case the lighting is three (left, right, and above) LEDs, of colour temperature 5300 kelvin (according to the stamp on one of them), shining through the white cloth sides and top of my collapsible photo studio, plus a bit of natural light coming in through a window off to the left. Since the two photos were taken 2:24 minutes apart, the daylight should be pretty much exactly the same in both.
 
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Jakko

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I’m afraid you’ve lost me …
 

JR

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I’m afraid you’ve lost me …
Your lost..... Jakko I was lost half way through. Glad two of you ( Tim ) know what your talking about.
I've spent hr's with my Cannon trying different settings, colour etc, still seems a minefield.
John.
 
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