Color Problems

[Neillo]

imann08,

No doubt we all understand and acknowledge that you know the basics and that you would prefer a less 'descriptive' answer without the need for highlighting the most basic of commands and actions.

However, please also bear in mind that some of us may not neccessarily have used these actions before in order to rectify our own colour problems—so these fuller, more rounded answers by the experts among us are a VERY helpful source of knowledge and expertise.

We should encourage fuller answers, not everyone is to your standard.

regards,
N.

[Gary Richardson]

As far as midtones being favored by the CCD, that is pretty much irrelevant as far as I know. If we are more sensitive to highlights than to midtones and shadows then it really doesn't matter what the CCD was favoring when it captured the shot.

But its the very data that that CCD produces that creates your picture, and is therefore the data that you are now manipulating in hope of getting things to look how you want. If the data is not consistant across the lighting of the scene (as will be the case if the light and dark areas are outside the linear response curve of the device), then you cannot "trust" the data for the light and dark areas to be accurate, and therefore cannot "balance them" to give a true colour corrected picture, the mid tone areas are the ones which will give the more reliable results.

This is of course a very much simplified explanation, as other factors will contribute to things. For example, the individual resposes of the R, G, B, elements of the sensor will also have some effect, the response curves for each colour are likely to be different, and will have been set up to be most "in step" with each other in the mid-tone frequency range.

If you're using numbers to balance things it is your eye response that is irrelevent (it would be all important if you were judging things by eye).

But as you are working with numbers, you want to work with the "best" numbers (ie the ones that are most reliable), and these are the ones produced when your camera's sensor is in its optimum response zone (ie mid-tone).


As for digital images needing only global changes, that is just not the case. As I've already described, sensor response is not the same for all colours in all light conditions. Further to that, sensors are more reliable in the central viewfinder zone, and trail of towards the edges, where the light is not hitting them at the same angle as it is in the centre (the focal distance is slightly longer towards the edges of the sensor).

Whilst this is almost insignificant in most normal lighting scenarios, it becomes more significant in poor lighting, and its these situations where more localised adjustments are usually necessary. It is also obviously affected by the focal length of the lens being used.

[albatrosss]

Swampy has a nice tutorial on this at:

http://home.earthlink.net/~lpswampy/

Works nicely with your photo.

[sunfly]

1) Separate layers for different elements

2) Levels

3) Curves

Cropping, cloning, dodging, neat image, and a final noise layer.

Thanks to all experts for all their tips. :-)


Sherry

[imann08]

Originally Posted by Neillo

imann08,

No doubt we all understand and acknowledge that you know the basics and that you would prefer a less 'descriptive' answer without the need for highlighting the most basic of commands and actions.

However, please also bear in mind that some of us may not neccessarily have used these actions before in order to rectify our own colour problems—so these fuller, more rounded answers by the experts among us are a VERY helpful source of knowledge and expertise.

We should encourage fuller answers, not everyone is to your standard.

regards,
N.

I was not trying to brag or anything like that. I will actually freely admit that many of the people on this board are much much better than I am. The only reason I said what I said is because I didn't want Gary or you or anyone else to have to take more time than was necessary to explain what they did. As with everyone, there are many times where I need drawn out explanations but if I can save someone a little time since they are already being nice in helping me then I try. I hope you understand my intent.

[imann08]

Gary, I think we may be arguing different points with the importance of midtones. If I get this correctly, I think you are talking about it in terms of it's darkness as opposed to the highlight's correctness. In that case, I would think you are correct. I was talking in terms of color. If you have some highlight that you can be sure is not only neutral but also the lightest part of the image, then it is more important that the RGB are equal than it is for the midtones because once it is printed out, we will notice the slight differences more in the highlights. So when talking in terms of color, what the camera picks up really is irrelevant. In the case of how high or low those RGB values are, which is where I think you are coming from, then it would be correct that midtone are more reliable since a camera focuses on those at the expense of the highlights. That's why highlights are often blown out in images from digital cameras. Of course, you know that, but I am just typing what I'm thinking.

My knowledge of the inners of a camera as you explained are somewhere between slim and none. What you said is interesting and I'll have to think about it for a while. I hope you agree with what I said in the previous paragraph.

[imann08]

albatross, thanks a lot. I'll take a look at that.

sunfly, that is an impressive correction. The only thing I disagree with is the removal of the background and how it leaves your image looking cut and pasted. That's not the important part of it though. At least as far as I can see, everything in the two people looks quite good. I'm impressed with the way the guy's hair came out and the baby's eye color. Very nice. Bravo!

[Gary Richardson]

Hi imann08,

Get where you're coming from now.

Yes, any colour imbalance will be more noticeable to the viewer in the high brightness areas, and so they must be correct.

However the best way to get colour balance for the whole picture in my opinion (and it is just an opinion) is still to get the mid-greys right first (for all the reasons previously stated), then do any final minor tweaks by balancing the highlights and shadows.

It may be that the final highlight adjustment "pulls" the mid-greys a bit, and that could be acceptable as long as the pic looks right, but adjusting the mid-greys first usually gets you into the ball park area faster. I've had some peculiar results when trying to balance things based solely on the highlights.

Usually I've had to adjust and readjust my curves before being satisfied that colour is balanced across all the lighting range, and there's almost always some compromise.

However based on what you say, I think I might experiment a bit more with letting the highlight settings predominate a little more than perhaps I have previously done.

[imann08]

Well, I am glad we were able to clear that up. We were just on the wrong page. I can definitely see what you are talking about and I sometimes go straight for the midtones in images. It isn't a black and white thing and really depends on the image. If it is a high-key image then going for the highlights first is probably recommended as they have to keep detail. Of course, to back up what you were saying, most images will lie in the midtone areas. Generally speaking, I pay special focus on the highlights, set midtone points in the curve based on the area of focus, and the then adjust and finetune from there. That doesn't mean that I don't start by attacking midtones sometimes though. It has a lot to do with whether or not the detail is significant in the highlights areas and the fact that I am very conscious of making sure that the color of the highlights are perfect first and foremost.

I enjoyed this back and forth with you. I always look at it as a learning experience and know that you are quite experienced based on the responses I have seen you make on this board over time.

[Gary Richardson]

I too have enjoyed our chat and profited from the experience, it's by talking things through like this that we all learn, and after all that is what this site is all about.