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Red is blown
When trying to photograph an orange or red flower and getting the exposure correct, how do you keep from blowing the red?.

Thanks in advance.Perspective is Everything..

Comments (11)

It allows you look at the exposure of each color individually. You still have to adjust the EV for everything as a whole, but you can make sure you're not blowing out any of the three..

There a pretty good example of this on Ken Rockwell's site:http://www.kenrockwell.com/tech/yrgb.htm..

Comment #1

I do understand that. But here's the thing. If I get the correct exposure then the red is blown while the blue and green is fine. If I go for the red everything else is off. Sooooooooooooooooooooooooo, since I've been forever exposing for the red channel I get underexposed images [not good]..

I came here so not to get flamed on the D300 forum for what on the surface is a newbie question, even tho' I am not a newbie. I've never been able to solve this delimma. Anybody out there have another answer?.

Again, thanks Tex! Perspective is Everything..

Comment #2

It sounds a little like you need to adjust white balance or color balance in post processing. Using auto white balance if there's an overwhelming color dominating might be the problem..

There's nothing very odd about this. No camera has been built that always gets color balance correct. Your main focus should be on avoiding blowing the channels, as blown channels can't be recovered later. If you avoid over exposing post processing is much easier..

StephenG.

Pentax K100DFuji S5200Fuji E900PCLinuxOS..

Comment #3

Pghaworth wrote:.

I do understand that. But here's the thing. If I get the correctexposure then the red is blown while the blue and green is fine..

In this situation, that is not the correct exposure..

If Igo for the red everything else is off. Sooooooooooooooooooooooooo,since I've been forever exposing for the red channel I getunderexposed images [not good]..

But, that is the correct answer. This is a case where dynamic range is very important to capture the lower exposed areas for post processing. Using whatever exposure headroom you have in raw above where jpg channels blow out is also helpful. Shooting these situations in jpg is very tough as the 8 bit color channels make is more difficult to work the lower light areas.Leonhttp://homepage.mac.com/leonwittwer/landscapes.htm..

Comment #4

Well, at least I have confirmation that I've been doing it right [if was you said is what I understood]. I always expose for the red [or the purple, if you will] so not to blow it but then I am underexposed. I do adjust all of those things in PP so we're good to go. I was hoping since I am an avid macro shooter that there was something I was missing..

Thanks for your help..

I opened the original raw file on this one and I had underexposed for the red so I guess I'm right in line. No masterpiece but I'm happy..

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window.

Thank you both. BTW it was great to be able to ask a question and not get flamed. There's so much I don't know about digital slr and so much I'm afraid to ask for fear of recrimination. You're the best..

Sjgcit wrote:.

It sounds a little like you need to adjust white balance or colorbalance in post processing. Using auto white balance if there's anoverwhelming color dominating might be the problem..

There's nothing very odd about this. No camera has been built thatalways gets color balance correct. Your main focus should be onavoiding blowing the channels, as blown channels can't be recoveredlater. If you avoid over exposing post processing is much easier..

StephenG.

Pentax K100DFuji S5200Fuji E900PCLinuxOS.

Perspective is Everything..

Comment #5

JPEG + intense reds + sRGB is asking for blown colors..

Of course the above should occur *after* you've established proper exposure..

______________________________________..

Comment #6

Sorry, I'm a red-head but I do have legitimate blonde roots. Please restate that like you're talking to a two-year old..

I always shoot raw, expose for the predominate channel and correct in ACS..

Perspective is Everything..

Comment #7

Now you've opened a can of worms. I was going to post this later..

I use ACS. I calibrated my monitor and now have a profile that differs from both my printer and my camera. How do I handle this. My incoming raw images are AdobeRGB 1998, my printer is Adobe sRGB and my monitor is calibrated to neither. When I import images into ACS it asks me if I want to ignore, convert or use camera CS. Which is correct? I have been answering convert..

Thanks for your gentle, non-judgemental help.Perspective is Everything..

Comment #8

Leon was probably just concerned that you were being limited by the jpeg processing in your camera..

Your method is sound - expose so no channel is blown..

Tricky part with red flowers is that often the blue channel is near 0 (no signal) so noise can be a problem..

Be sure to properly white balance, too. And, calibrate your ACR (discussed often on these forums.).

Under artificial light problems become even worse... so be sure to shoot in good light..

Note that the human eye is easily fooled by "red" too. We cannot judge red saturation very accurately by eye. You can use that here to lower the saturation and luminance of a red flower a bit in case your raw conversion is still getting you blown 8-bit values, and yet to the human eye the flower will still look red. ACR has tools to adjust the saturation of colors..

-gt..

Comment #9

Sorry to be obtuse. In most cameras, you can expose where a color channel histogram is jammed up against the right. In recent Canon cameras, for example, there is a bit less than one stop of exposure "headroom" beyond where the color channel histogram hits the right boundary of the histogram. With practice, you can learn to judge how to get this extra exposure. This is an extreme version of "exposing to the right." In cases where you have a strong red channel, this extra exposure can help do a better job in the other channels as the more light you capture, the better..

The amount of extra exposure that you have is also a function of the raw converter you are using and how good it is in accessing the extra exposure range. I use Adobe ACR which is quite good in this respect..

In sunlight with the proper WB, exposing a stop below where the camera image begins to flash on the red object will keep the red channel from blowing out assuming you do have the one stop of exposure headroom. This is because in sunlight, the red histogram will never be more than about 1.7 stops farther right than the luminance histogram. A bit of experimentation with sunlit red flowers against a dark shadow background is a good test setup.Leonhttp://homepage.mac.com/leonwittwer/landscapes.htm..

Comment #10

Pghaworth wrote:.

I use ACS. I calibrated my monitor and now have a profile thatdiffers from both my printer and my camera. How do I handle this..

This is the normal situation..

My incoming raw images are AdobeRGB 1998, my printer is Adobe sRGB andmy monitor is calibrated to neither..

Generally, a printer will have it's own profile that does not match any conventional color space. Most manufacturers provide color profiles for their printers and OEM inks and papers. For other combinations, you may be able to find profiles on the web..

When I import images into ACS itasks me if I want to ignore, convert or use camera CS. Which iscorrect? I have been answering convert..

If you are using PS, you establish a working color space in the color settings. This is the space used by the software while you do PP. If you use Adobe RGB in your raw conversion, then it is a good idea to select the same for your working space in PS. Then you will not get the warning/question..

Generally, the display profile will be different from your software working color space which, in turn, is different from your printer profile. In this context, profiles just define the color spaces of the display and printer. This all works because a color management aware application like PS has a color management engine that will convert (translate) your images however necessary to the profiles (device color spaces) when images are sent to the device (display or printer). In PS, the color settings do allow some control over the conversion process when an image goes to a device. I mostly use "relative colormetric" and black point conversion. That is another discussion.Leonhttp://homepage.mac.com/leonwittwer/landscapes.htm..

Comment #11

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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