Blowing Red Channel

I have this constant struggle with blowing red/orange/pink in camera. Sometimes it's recoverable in ACR, sometimes not. HOW do i work with this? For example, I practiced on hubby in a bright orange shirt and if i exposed to not blow the shirt, you could NOT c his face. so i exposed to see his face and his shirt isn't recoverable in ACR. Am i limited b/c i don't have a flash? or is something else the answer... I've tried uppping my ISO. differnt f/stops and different ss. I have the d300 which i read is notorious for blowing the red channel....?? I shoot on Standard and Neutral settings....<br /><br />Any thoughts/comments GREATLY appreciated.

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<p>Seems very unlikely that an orange shirt and facial skin would be so far apart in reflectance that one would be blown and the other grossly underexposed (assuming they were both illuminated to about the same degree). Posting the photo would help. When you open the image in ACR and check the histogram, is it only the red channel that is blown?</p>

<p><img src="http://i876.photobucket.com/albums/ab322/DealGirl19/adam.jpg" alt="" /></p>

<p>excuse the dirty shirt/posing. just trying to get this problem figured out...<br>

this was f/4 1/250 iso 800 had to bump iso to get ss. <br>

in ACR ONLY the red channel is blown. the other channels are FAR left.... </p>

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<p><img src="http://i876.photobucket.com/albums/ab322/DealGirl19/screenshot.jpg" alt="" /><br>

screen shot of ACR. </p>

<p>I can't quite make out the info in the second image - is that sRGB color space and 8 bit? If so, try using AdobeRGB or ProPhotoRGB for the RAW conversion - your red channel will not be blown then and is easily recoverable. Convert to sRGB (for web display) and 8-bit (for JPEG) later in PS.</p>

<p>Yes, use 16 bit and either Adobe RGB or proPhoto RGB; also, shoot in 12 or 14 bits; more bits are good, since more information is captured; and, when in PS, edit in 16 bit mode.<br>

Your highlights are clipped in the red channel and shadows clipped in blue channel; so, move recovery and black sliders to correct for clipping; you want your pixels distributed between the "end" lines of the histogram or when no clipping occurs. ProPhotoRGB space is wider than Adobe and may help correct red and blue channel saturation clipping too -- along with the recovery and blacks adjustment<br>

Move the clarity slider to the right -- about 50; check how this affects mid-tone contrast on histogram; adjust recovery as needed to avoid clipping.</p>

<p>Another trick for you: in the workflow options (bottom center -- shows color space, bit depth, image size, etc) when you select ProPhotoRGB, also check "open in Photoshop as Smart Object". When the image opens as a smart object in PS you can double click it and return to ACR , in PS, for finer adjusments; or blend it as you would any other layer.</p>

<p>Suggestion 1: When red is prominent in the scene, under-expose (i.e. bracket).</p>

<p>Suggestion 2: Desaturate the image by pulling ACR's Saturation slider to the left. Saturation boosts the red channel.</p>

<p>In my experience, shooting in aRGB color space one has much less red channel clipping. You can choose aRGB color mode in camera, shoot RAW, then in PP change back to sRGB and reduce exposure to preserve reds.<br>

Another technique is using UniWB. It's a white balance preset which allows you to see the true RAW histogram (in R,G,B) captured by the sensor. The RGB histogram in the LCD you see is the one after WB is applied and is not a true RAW RGB. If you're interested in this try google UniWB. It's a bit too difficult to explain in one post.</p>

<p>1) Use a color compensation filter to reduce red.<br>

2) Use UNI WB to adjust the sensor and to get a reading of the true histogram and/ or bracket exposure.<br>

3) Use prophoto rgb in 16 bit for conversion and first steps in post processing.<br>

4) Try different raw converters. Adobe ACR is actually better than Nikon NX2 software to recover highlights but once you used the filter the channels are about even in exposure and you will not need to recover highlights so much.<br>

5) Do not use brightness +50 if you already have blown highlights!<br>

For 1) + 2) you will need to set WB manually in post processing. It will be way off but this is the intention to protect the red channel.<br>

What is your camera? A D3 is more tolerant to pull up shadows than a D40.</p>

<p>BTW: It is a good idea to get images right when shooting rather than to correct mistakes in post processing. Does the person own another t-shirt with less bright colors? How about a medium gray shirt and a fill light? This will not help for snaps or if the purpose is to sell extremely bright t-shirts :-)</p>

 

<p>What kind of camera? Fact is, the single-channel histogram in my D50 doesn't show when you blow out the reds, as it's simply a histogram of the green channel if I recall correctly.</p>

<p>So... under-exposing slightly when you have a lot of red, as Dan South mentions above, is the answer.</p>

<p>It's a D300 as the OP says at the top.<br>

Standard practice would be to back off the exposure (and in this case back off the ISO from 800 too) until the red in-camera histogram looks OK. Lift any shadow detail lost etc. by post-processing.<br>

The shirt isn't fluorescent is it? That would make it kind of super -reflective!</p>

 

<p>So far, all the suggestions are desktop post-processing.You can also try some in-camera setting?</p>

<p>What PictureControl mode were you using? Try Portrait or Neutral may help to tame the colors.</p>

<p>Also, if you want to stick to Standard/Vivid mode, you can adjust the tint to make it more tilted to green than red. And, you can also adjust the Saturation to lower it.</p>

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<p>Sometimes it's recoverable in ACR, sometimes not.</p>

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<p>There's your answer.<br>

While PP can often cover a multitude if sins, it should not be a crutch for improper shooting technique.<br>

Yes; primary colors are a challenge to digital.<br>

Carefull control of light will go a long way to off set this problem, such as; shooting in shade where the bright sun is NOT reflecting the primary color so hot.<br>

Reflectors to add light to the face while easing off on the exposure (the shirt in your case) will go as long way to a better balanced exposure.</p>

<p>I hope I don't get flamed; but 9 times out of 10, these shooting challenges can be handled with some thought <strong>before </strong>we squeeze the trigger.</p>

<p><em>"Good Enough"</em> and <em>"I can always fix it in PS later"</em> is not the mind set to have if we hope to become better photographers.</p>

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<p>Jessica.... Simply use the RGB histogram that you paid for in the D300, set the reds to flash blown highlights, and dial back the exposure until the red channel isn't clipped. </p>

<p>In a strong green scene, set the highlights to the green channel. In heavy shade, set the highlights to blue since they'll each go first in those situations. There are exceptions, such as the vivid sweatshirt your husband is wearing in otherwise bluish light, but try the different colors and use that tool that is literally at your fingertips.</p>

<p>LOTS of good info here. It was a safety orange shirt since he had just got off work and i was wanting to practice. so probably not a color i'm going to run into alot (hopefully) but i've had the SAME problem with pinks and reds..<br>

I USED to process in RGB but my pics looked dull and not as colorful? I never understand how if it's going to be blown in sRGB how PP in RGB and converting it still wont blow itAT conversion?? u know what i mean?? <br>

I def. use my RGB histogram when shooting ... theproblem was i would have had to dialed the ss up to 500 or so to now blow the shirt and then the pic would hae been SEVERALY underexposed. <br>

that was my MAIN ?. what do u do when u would have to SEVERLY underexpose a image in order to not BLOW highlights???</p>

<p>Walter - on the brightness being set to 50. my acr opens that way and i thought it was default?? should my numbers b set to soemthing else? i had not adjusted ANYTHING on the screenshot. it opens every picture the same...</p>

<p>thanks guys!</p>

<p>The camera sensor is most sensitive to green. So in most cases, if the green histogram is ok (not blown) and you're shooting RAW, the other channels are fine too. Problems arise when White balance is applied by the camera, in which red and blue channels are multiplied (sometime by a factor of >2) to compensate for the weaker sensor sensitivity. The multiplication cause blown channel, not the RAW data itself.<br>

Underexpose is a natural way to avoid blown red but obviously not the best (noise now becomes a problem).By underexposing you don't use the sensor capacity to its full potential.<br>

If you feel bothered to dig into technical details (aRGB vs SRGB, or UniWB) then just go with underexposing method. I used to do so, too.<br>

Regards</p>

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<p>Why use ISO 800; ss 1/250? This scene could have been shot between 1/60 and 1/125 sec with no problem, with half the ISO noise; also a larger f-stop ~ 3.5 might be useful for the portrait by blurring the wall in background.<br>

In camera options on D300 are many:<br>

Legacy light meter method: Try manual mode, single-point AF; spot metering (on the top switch next to and right of eyepiece); be sure you can see focus points in viewfinder; move focus point to an area with highlights, and note exposure in viewfinder; move the focus point to and area with shadows and note exposure in view finder. Note differences in exposure. Set aperture and shutter speed, manually, some where in between those extremes. Shoot! Do the same thing center weighted and matrix. Keep and compare images. Note: you can adjust center weighted sampling area to expand or restrict exposure area. This method is not perfect.<br>

In camera auto-area AF method: do the above using Auto Area AF (switch on right next to bottom).</p>

 

<p>Thanks Frank and Huy...</p>

<p>Frank i never thought of doing a meter on the hghlights and then the shadows and going inbetween. VERY smart!!! love it!! will try that out asap! Also, the reason i went with the high ISO is i was told i need to keep my SS above 200 to get sharp pictures and nice portraits... guess that isn't alwasy so?</p>

<p>"Walter - on the brightness being set to 50. my acr opens that way and i thought it was default?? should my numbers b set to soemthing else?"<br>

Jessica - the sliders are there to be used :-) Yes it is a default that works OK depending on the camera profile that changed with version. But ONE default does not work well for all shooting conditions. Try and play with all sliders and compare shots taken in dull weather in in bright sunlight. You will quickly see that you can get best results with different settings for the two conditions. You can safe your most liked settings for your most frequent shooting conditions and recall them when needed. ACR even lets you set different default values for different ISO settings. These are often useful to set starting points e.g. for noise removal and sharpening. There is an excellent book on ACR by Bruce Fraser and Jeff Schewe that you might want to get from your local library.<br>

http://www.amazon.com/Real-World-Camera-Adobe-Photoshop/dp/0321580133/ref=sr_1_1?ie=UTF8&s=books&qid=1256335207&sr=1-1<br>

If this is a bit too technical browse for similar books, there are other ones that are also excellent.<br>

Whether you do most adjustments in import in the ACR plugin or just try to keep as much information in import and then do most work to optimize in PS is more up to your taste and experience. And do not despair - it is a never ending learning experience with a difficult start :-)</p>

 

<p>Jessica,<br>

Something else that might have happened. You actually might NOT be blown in R. As others posted, set the color space to Prophoto (the largest gamut), and depth to 16 bits. Set contrast to zero, and go to the curves tab and set that to linear. Then reduce exposure by a stop or 2. If there's no peak on the right end of the histogram, you have NOT blown any channel. If the RAW data is clipped, there will *always* be a peak at the right side of the histo, but it will move left as you reduce exposure.<br>

You can also use the WB and many, many color tab controls to reduce the effect of clipping a single channel. Be sure to try other camera profile names as well. Adobe might have created some Velvia-like color tweaks...</p>

<p>Lad - this is what is SO confusing to me. and frustrates me to NO END. I MIGHT be blown.. that's a very "iffy" situation, kwim? I mean i don' thave a computer with me when i'm shooting so that makes it hard to know if i'm really blown. and waht if i am and it's unfixable.. i need to know what AT the session. not when i get home. How do i fix that?</p>

<p>This is the link to download UniWB preset for D300<br>

<a rel="nofollow" href="http://www.pochtar.com/Nikon_D300_NearUniWB.zip" target="_blank" >http://www.pochtar.com /Nikon_D300_NearUniWB.zip</a><br>

Copy the picture in this file to your CF card. In your D300 menu choose Preset white balance from this file. Take a test shot with this WB preset and check the channels. If set correctly the photo will have a dominant green look. Once you see no channel clipping, you can return to Automatic WB (or whatever WB) and shoot with the same setting (aperture/speed), confidently.</p>

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