RGB, Luminosity, and Black Point

I have an image shot in a forest, with a footbridge over a stream and a path in it. It has a lot of green, naturally, and a few blown out places in addition to dark shadows. While I like it, I've always found it a little flat.
Looking at the histogram under levels adjustment, the left side of the "mountain" is right up against the zero point of the graph, so I never bothered to try tweaking it.
But yesterday I noticed that, if I use the histogram palette and change the drop-down box to "Luminosity", then the left side of the mountain is a bit to the right of the zero point on the graph. Curious, I switched to the levels adjustment, selected the black eyedropper, and clicked in the darkest part of the image that I could find. The colors became much deeper -- especially the greens -- and even the blown out parts look better. Some of the shadows are maybe a bit too dark, but overall it's a nicer photo. And I noticed that on the histogram palette, the luminosity mountain is up against the zero point of the graph now.
So, finally my questions. What exactly is luminosity? And is it always preferable to use the black eyedropper rather than the little slider on the levels adjuster, as I had always done before? Is there a way to see a luminosity "mountain" in the levels adjuster, rather than just RGB or the individual colors? And for that matter, what is RGB?

"What exactly is luminosity?"
Luminosity is a representation of the brightness of an image separate from the color/hue. A histogram of the luminosity will show a pretty reliable map of the tonal range of an image. Adjusting the range of the red, green and blue histograms so they cover a full range of tone may be a better correction in Levels than using Luminosity mode as the r,g,b sliders will correct for some color casts and shifting that luminosity will not.
"And is it always preferable to use the black eyedropper rather than the little slider on the levels adjuster, as I had always done before?"
I would stick with the slider adjustments. The eyedropper is convenient, but not easy to control, and not as accurate.
"Is there a way to see a luminosity "mountain" in the levels adjuster, rather than just RGB or the individual colors?"
If I think about this, there might be an easier way, but this will give you the right view of the histogram:
1. Create two new layers at the top of the layer stack for the image you are working on. Name the bottom of these two layers Commit and the upper Source.
2. Activate the Source layer and stamp visible to the layer (Ctrl+Alt+Shift+E/Command+Option+Shift+E [PC/Mac]), then set the layer mode to Luminosity. At this point the image will look the same.
3. Activate the Commit layer and fill it with 50% gray (Use Edit>Fill Layer). After the fill the image will appear to be grayscale.
4. Activate the Source layer again and merge down. Name the resulting layer Luminosity.
5. Create a new Levels adjustment layer and view the histogram. You will see that this result is a somewhat different representation than you get from the RGB graph.
"And for that matter, what is RGB?"
RGB is red, green and blue...it is a light-based color model where the set of these three colors mixed in different amounts make up the total set of available colors. 100% of red, green and blue is white, 0% of each is black and even amounts of each is gray (at varying brightness depending on the percentage). RGB theory is what much of digital imaging is based on and much of what my book relies on to help people with color and other corrections.
Richard Lynch

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White and black point vs ??

I never know which forum to post these things, so I'll start with the photographers.
 
 These three shots are as follows: (1) the camera raw version, (2) where I moved the sliders from the ends to approximately the beginning/end of the major portion of the histogram, and (3) using the threshold control to find the white and black points in the main part of the picture.
 
 Then, in the two adjusted versions, I lightened the image with the curves control.
 
 In both these cases, I used the grey dropper to touch the same spot on one of the rocks, to get the apparent neutral point.
 
 It seems to me that the threshold method to find the white and black points is preferred, based on the overall color and appearance of the finished adjustment.
 
 But, I've found on some images where the histogram has missing black and missing white, if I adjust the sliders to these two ends, I get pretty much the same outcome, as far as the contrast, color, and grey point.
 
 Could I have some advice on the preferred method to use in handling my image adjustments? Doing it the threshold method takes more time, and sometimes it's difficult to find the white and black points, or even the grey point.
 
 Thanks.
 
 Al
 
 
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Yes the image was purposely underexposed. What I was trying to accomplish was to speed up the shutter speed to remove the slight blurring and compensate by pulling data from the shadows. Even though the lens has an image stabilizer the amount of light wasn't enough for a proper sharp shot.
this image is before touch up
These two images are F/5.6, 1/20, ISO 800
After touch up
Better lit scene but shows slight motion blur
This last image is F/5.6, 1/4, ISO 800
I believe that I will have to wait next year and hope I have a faster lens by then. I just don't think the 28mm-135mm f/3.5-5.6 lens is fast enough. I was trying this without a tripod to get in tighter.
Also I was taking these shots without the flash to get the drama of the tree lights.
What I would have prefer is a shutter speed of 1/125 or better as it helps with my hands shaking I believe the slowest should be 1/60
And the lower the ISO the better for noise.
These preferences are what I am used to with my Canon G3 that does not have IS.
I am getting so off track here, lol. But anyways, here are the pictures.

Recovery, and Black Point Not Working in 2.0

I imported RAW pics from my old database (converted to 2.0). Wanted to try the new exposure adjustments, mainly recovery and BP. The HUD only lets me adjust exposure and brightness, the recovery and black point are grayed out and cannot be adjusted.
Has anyone got this adjustment to work? I am using the trial version. No, I am not in the preview mode. The master is Canon RAW from 40D.

Got it. Thanks! Just figured it out too that you need to choose the v2.0 RAW conversion on the RAW Fine Tuning adjustment toggle.
Recovery and BP adjust a lot more sluggish on my MBP w/4G Ram then it does in the tutorial video. This is concerning since in have only imported about 40 pics so far.
Time will tell.

Aperture2 - Recovery and Black Point adjustments question

I purchased the Aperture2 upgrade and, I'm impressed!!!
I have a question:
In the *Adjustment Tab*:
Two features in the *Exposure area, "Recover and Black Point"*, works sometimes and other times it does not.
There must be a reason for it - I just can't figure out why this happens. One would think that it should work all the time!?
Anyone know?

C and Scott, thanks so much for trying to help this old codger learn new tricks.
All the images I imported into Aperture2 are projects already completed and therefore I won't need to make adjustments to them. I was using them to test and learn the new Aperture2 features.
But, Just in case I ever need to convert a RAW image from A1x to the A2 format I'll know how to do it.
As I said before, as long as my new RAW images that I import directly into A2 have all the features available, I'm a happy camper. I won't be importing any images into A2 until after my shoot this evening, so, do you know if this is the case?

Recovery and Black Point on JPEG images

I'm not a big fan of trying to do much editing on JPEG images aside from non-exposure/white balance type stuff. I'll crop and straighten, etc.
My question pertains to (for those in the know) applying slight Recovery and Black Point correction to images that aren't shot in RAW format. A) will applying these slight changes having any effect (hopefully a positive one) on the images? B) if not, will it indeed have a negative effect?
Thanks for your time and expertise.
Mac

Jim,
Thanks for chiming in on a topic where I didn't expect to get many replies. All of your comments are well appreciated. I was basically asking because I was under the impression that unless your master is in RAW format, making adjustments to exposure, contrast and even recovery and black point would not do much and could even be detrimental to things such as skin tone, etc. I like to shoot in RAW for the reason of being able to have more fine control to adjustments, but for everyday shots and portraits I don't always go to RAW format since a lot of the time I have trouble getting the shot right with the manual controls. I also don't want the large RAW files for every shot that I take. Still, a lot of JPEG's need adjustments, even if just minor tweaks. The tweaks I make look fine on the screen, but I wasn't sure if they would look okay when printed out and I didn't want to spend countless hours making adjustments and spend (waste) money on prints that weren't going to come out good.
Anyway, that is the background to my thinking in making this post. Thanks again for chiming in.
Mac

Setting a White Point and Black Point

I would like to suggest for future versions of lIghtroom to have an ability to set the white point and black points similar to levels and curves in Photoshop. This would be in addition to setting middle grey in the white balance settings currently in Lightroom. I find that the method of using Threshold to find the closest white and black pixels and then using these points to set the black and white points in curves or levels provides a better way to fix a color cast than the methods available in Lightroom.

MB,
There is no real need for Black and White point eyedropper type tools in Lightroom. By holding down the Alt key while changing the Blacks or Exposure sliders the display will show the areas that are being clipped. This is much faster than looking around for the darkest and lightest areas manually. If you just like to click to taste (like using the White balance dropper) then forget the Alt key and just move the sliders until you get the desired look.
Remember that the problem with Photoshop is that there are so many ways to do the same thing that it has become difficult and bloated. Lightroom strives to keep the interface as clear as possible.

Setting White, Mid and Black Points in Camera Raw 7

I am using Camera Raw 7 and can not seem to locate where can you set the white, mid, and black points in Camera Raw with the eyedropper tool. It seems you have to create a new psd file in Photoshop to do this, which does not make much sense since it is a basic levels adjustment. I am batch editing a bunch of CR2 files, and I just need to select the black, mid and white points on a grayscale that I've shot in the images - is there a way to do this in Camera Raw 7? Thanks!!

ACR doesn’t work that way. There is an eyedropper for the overall white-balance that you can set by clicking on a relatively bright, neutral area, but there aren’t black and white-point eyedroppers. But, what is clipped black or white is determined by the output colorspace you have set at the bottom and you can get some idea of what will be clipped black and white by turning on the clipping indicators and watching for the areas you’d be eye-droppering on (the black and white patches in your grayscale) to start showing the clipping color overlay for black and white, but any further toning adjustments will move data in and out of what is darker than black and lighter than white so what is clipped for output will change as you fiddle with the various toning sliders.
The reason things are different: In PS, when you set a black-point and white-point in Levels and click Ok, the data below and above those is thrown away and that is the starting point for the next adjustment. In ACR, things are non-destructive and all the adjustments occur simultaneously, rather than sequentially as in PS, and no clipping occurs until you create the output file. This means that the pixels that are darker than your black-point and lighter than your white-point are still there, and can be moved into the black-to-white range if you do further toning adjustments. Having more headroom of the pixels that are outside the black-to-white range is good because you won’t get the posterization or banding that occurs when colors and levels are clipped after each adjustment in PS.
Can you describe what you intend your overall workflow to be on an image: how much adjusting will occur in ACR and how much, if any, might happen in PS, after the image is opened into PS from ACR, or opened from a file saved from ACR? There might be other ways to approach what you’re trying to accomplish.

Establishing White Point and Black Point

Hi,
How do I Establishing a White Point and a Black Point in Lightroom 1.4.1 and especially in Lightroom 2 Bata?
Thank You,
Hersul

The last post by OP might have closed this thread, but given the relative lack of activity on this and LR2 forums (summertime?) - I'll go a little deeper.
i White point
- If your white balance is right from the start, you just use the Exposure slider to set the white point. If not, first set the white balance - that effectively sets a preliminary white point for each channel separately, or, to be more precise, matches the right side of the histogram for each channel - then set the Exposure. So, with the white point you have complete control over the histogram, as well as over each channel.
i Black point
- here the situation is different. You can move the left side of the main (composite?) histogram using the Blacks slider, but there's no means for moving channels separately. In theory, with digital capture, there probably should not be need for this, blacks should be always black, so that's OK, but...
I once had a batch of pics scanned from film. The film was poorly developed so it has some strong brown-magenta cast in the shadows. In Photoshop it was a piece of cake to set the black point by dragging the left ends of each channel to the left edge of the histogram (heck, even Auto Level did a wonderful job). In Lightroom, there's just no way you can correct this, because you can't control the channels separately.

Highlight recovery and Black point sliders greyed out.

Hi
Does anyone know if there is a reason that the recovery sliders would be greyed out and non functional for my images.
I have not been able to utilise this function in version two.
NW

did you migrate your RAW files to the new RAW 2.0 convertor ???
i believe that if left at the 1.1 it will prevent you from using the new features ...
migrate is under the file menu ... and can be done project by project, image by image or the whole library at once (very freaking slow if large library) ...

Recovery and Black Point sliders not available

Hi, I notice that these sliders are not available for RAW files that were loaded onto Aperture 1.5. Is there something I can do so I can make use of these sliders?
Cheers,
Mike

Yes. Migrate the image to which you wish to apply these two adjustments to the 2.0 RAW converter. Mind that your colours may shift; possibly the best way to do this is to remove all adjustments first; this will also cause the image to be interpreted by the 2.0 RAW converter.
Cheers,
k.

Setting black and white points

Dear friends,
I am shooting some pics with a "Whibal like" target card which has a white, black and 18% neutral grey shades.
In Camera Raw I I can easily correct the white balance with the provided eyedropper on the top row by clicking on the grey target.
I cannot find any way to set the black and the white points though and have to resort doing that for EACH picture in Photoshop via a levels or a curves adjustment layers.
It would be great to be able to set those in Bridge/Camera Raw so that I can then copy those settings to other similar shots.
Any ideas ? Thank you
Marco

I am having the same problem, although its now Camera Raw 7 - where can you set the white, mid, and black points in Camera Raw with the eyedropper tool. It seems you have to create a new psd file in Photoshop to do this, which does not make much sense since it is a basic levels adjustment. I am batch editing a bunch of CR2 files, and I just need to select the black, mid and white points on a grayscale that I've shot in the images - is there a way to do this in Camera Raw 7? Thanks!!

Adobe CMM Black Point Compensation

Hello list members,
I have been trying out the Adobe CMM in combination with Adobe Photoshop.
By testing the Black Point Compensation (BPC) preferences, I get strange
results on my PowerMac. This is not happening on an IntelMac for me.
The discussion started on the ColorSync users group and is still going on there,
so maybe others might report there too.
This is my testing basis (All done with ISOcoated to ISOuncoated, relative colorimetric):
(Abbr. Adobe Photoshop Convert to Profile BPC Setting: PS)
(Abbr. Adobe CMM preferences BPC setting: CMM)
PS CMM Expected Happening
On On BPC taking place OK
On Off BPC taking place NOT Ok, no BPC happening
Off On BPC taking place OK
Off Off NO BPC OK
Any feedbacks are welcomed.
Regards
Rolf Gierling

In rare cases using Black Point Compensation can cause unacceptable results and the effect is usually washed out detail in the very dark regions of the final image. In our experience this problem usually rears its ugly head with some RGB output profiles.
Adobe recommends, and we agree, that in almost all cases, Black Point Compensation should be on when dealing with CMYK files (doing
RGB to CMYK conversions or CMYK to CMYK conversions). In most cases, doing RGB to RGB conversions without Black Point Compensation will produce desirable prints. However, depending on the profile, doing a conversion from RGB to RGB with Black Point Compensation can produce
poor output with washed out blacks.
It appears that this problem with some RGB profiles is dependent
on the software that is used to generate the profile. Apparently there is a Black Tag feature in ICC profiles that in some cases can be used or unused depending on the software that actually creates the profile. For this reason, there is no hard and fast rule that says we should or should not use Black Point Compensation with RGB output. Our recommendation is to turn off Black Point Compensation with RGB output profiles or if possible, try a test with Black Point Compensation
on and off.
There is one other case where you may want to turn off Black Point Compensation. When you want to soft proof output for a printer that has a low dynamic range like newspaper, where the blacks are
usually not very dense. By turning off the Black Point Compensation, the soft proof is more accurate in predicating the effect of this low dynamic range. Black Point Compensation should be turned off
in the CMYK Set-Up. You can view full information for this problem source www.digitaldog.net/files/Black_Point_Compensation.pdf
Sincerely, Shair

White point / black point

Just like with Photoshop's Levels and Curves I would like to see a White point and Black point setting ability.

I'm aware of that, but I find that many times it's an easy way (in PS) to determine what I really want to be white (the white of an eye, for instance), at least as a starting point. Using the LR exposure slider to do so is less convenient and doesn't give me that instant and exact control.
Since I am very often using black as a background, it would be convenient to pinpoint that as black.
And now we're into it: why just not call the LR selector what it really is: a Neutral selector? Its shifts colors to neutral grey like in PS.
B.T.W.: I also often use a neutral grey background (18% reflection) and that's where the "White balance selector" is of a very great help.

When to set white/black point

Hello,
My apologies if this is a dumb question.
I am new to Photoshop and am making a start on tidying up all my photos. I am keen to establish a good workflow but am unsure on which steps to take first.
At the moment after opening up my image in Photoshop, I first check the histogram and then if necessary use the sliders in Levels to make any adjustments.
I've started trying to set the white/black point values too but am unsure as to when to set them. Please can anyone tell me whether I should take a sample of each at the very beginning before I make any adjustments or at the very end.
Many thanks.

First of all one should apply Adjustments as Adjustment Layers and the fewer the better as regards potential banding (but this can occasionally be alleviated by switching the layered version to 16bit).
It may be a matter of taste, but if one does use the white- and black point I’d rather have it used at the beginning (or farther down below as an Adjustment Layer).
Additionally I’d recommend trying to do as much of the global Adjustments as possible with a single (Curves-) Adjustment Layer.

Setting White/Black Points using the Tone Curve

I'm trying to set white/black points using the tone curve, but when I try to slide either of the end points of the line in the tone curve tool I can't get them to move. Could those be locked somehow...?

That's what it is supposed to do. Without the sliders, you are working with the curve itself. Now you have direct control of the curve, and can drag any part of it. Have you considered setting your white and black points using the whites and blacks in the basic panel while holding down the alt/opt key? I suppose the reason it says point curve is because that icon is what you used to switch to the point curve.

RGB, Luminosity, and Black Point

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