Red Highlights

[Dumien]

I usually take pictures of flowers in my back yard because my mom loves them. I usually find myself dealinf with a problem in the red channel: more often than not, I encounter a problem with saturation of the reds in the highlights. I usually shoot in the morning or in the evening, because the light is less harsh and always use highlight tone priority.


Here's an example, first the whole picture, then a crop of an area involved in the problem.


canon XSi, 24-70mm, 1/320sec, F5.6, ISO 100, 57mm







Usually, some saturation and curve adjusting is enough to get rid of most of these phenomena. BUT, what would you suggest to prevent this kind of things happening?

[alex]

any chance you're shooting with the Landscape setting, instead of Standard? I find that the Landscape setting on my XSi often over-saturates the colors.


I didn't know the XSi had Highlight Tone Priority. I need to look at my manual again, I guess.

[john-pa]

I shoot a lot of flowers too, and I often see this effect. One of my early theories was that the IR wavelengths were fooling the camera’s metering, and I tried using an IR-blocking filter, but that did nothing. These days, when faced with highly saturated reds, I just make a point of doing at least -1ev, and that usually solves the problem.

[Daniel Browning]

It looks like you're referring to the blown reds. Many times the red channel in the raw file itself is fine, but gets blown during raw conversion: especially applying white balance or during color space conversion (i.e. sRGB). It appears that you used DPP, which can exhibit this problem too (although I recall it has pre-WB linear EC, so you could work around the first problem by applying a nonlinear EC curve in Adobe after conversion).

I suggest posting the raw file (e.g. yousendit.com), then one of us on the forum can show you what it looks like in a different converter (or in DPP with different conversion parameters and post processing).

[Dumien]

any chance you're shooting with the Landscape setting, instead of Standard? I find that the Landscape setting on my XSi often over-saturates the colors.


I didn't know the XSi had Highlight Tone Priority. I need to look at my manual again, I guess.
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Yes I almost always shoot in Landscape setting, because I like how it renders colors, but I usually try all of the settings out when I'm post-processing. This one was converted using the picture style "faithful"


Daniel,
can I send it to you? Could you give me your email? Thanks


Andy

[Daniel Browning]

Andy,


I sent you my e-mail address(es) in a private message ("conversation") using the forum, but I haven't heard back. Just in case you didn't get it, here it is: db (at) kavod (dot) com. (What's another 100 spams per day? I already filter thousands.)

[Don Burkett]

Reds, purples, yellows, oranges, are all difficult colors to render perfectly. They are so saturated in color it's easy for them to blow out. Most especially anytime they are in direct sunlight. My suggestions are spot meter then go to manual mode, start with an exposure compensation of -1 and keep heading south until you get the accurate color. If you get to -2, use a diffuser and start over. By the way, when these same colors are in full shadow, getting accurate color is still an experimental process, partitcularly in the deeper tones. In short, in most cases do not rely on the camera's default settings when shooting these colors when their fully saturated.

[Daniel Browning]

After Andy got back to his computer he sent me the raw file. Here it is for anyone who would like to take a crack at it:


IMG_0019.CR2


I took a quick glance and it is just as I expected: the raw file itself has absolutely *no* clipping in it anywhere. (I checked with Rawnalyze.)


In fact, it is *underexposed* by 2 and 1/3 stop! Yet when I open the file in DPP, the reds are immediately clipped. This is a very clear case of a raw conversion gone horribly wrong. The good news is that it can be fixed.


The white balance settings include "push RED channel by 2.29 stops", so most of the clipping is probably happening during the application of white balance. I will see if I can get DPP to do a more sane conversion. If not, I'll show what it looks like in a different (better) converter.

[Dumien]

maybe this might help:


in DPP I upped the exposure by 0.33 and then applied kelvin white balance to 4600 degrees. neither contrast nor saturation were applied. Raw sahrpness to 7 and RGB sharpness to 80...


I think that's all I did ^^


thanks for the help


Andy

[Daniel Browning]

Keep in mind that I'm no post-processing expert. I can only prove that better processing is *possible*, not actually do it myself.


I couldn't get the results I was looking for in DPP (I don't use it much), so I did quick run with RPP:





(Full size image)


I'm sure an expert could do much better. The color is obviously very different from yours. But at least it proves that the issue is entirely contained to raw conversion and post processing. It's not a camera or exposure issue. In fact, the shot could be exposed 2.3 stops hotter without blowing any highlights. (In this case that's not important since the image clearly has sufficient DR and noise, but it helps to know that for other cases that do need more DR and less shadow noise.)


Going back to your original question: the best way to avoid this problem is to wait for technology to come up with computer displays that are capable of reproducing the same colors that occur in real life. Of course, they will probably invent teleporters and space travel first, so in the mean time we have to work with software to try and find ways of mapping those extremely saturated colors down to the limited level that monitors are capable of. But since I haven't really learned enough about this stuff, the best answer I can give you is probably "I don't know."