how to know colour levels are between 4 to 250

<p>hello<br>

i use cs3. i shoot raw and edit photos in camera raw. while editing, i would like to know that my RGB is between 4 to 250.<br>

in camera raw, when i look at the histogram , it does not tell me the value on either the white or the black side. the same is when i open the image in photoshop and look at the histogram.<br>

how do i know my rgb is between 4 to 250? please can someone let me know. thank you.<br>

cheers</p>

<p>its not that you always really want those number personnaly, but what you need is a perfect black with details and a perfect white with details.. to get that in Lr or ACR, simply press and hold the ALT key while at the same time using the exposition cursor ...</p>

<p>WHITE/ you should get a black screen to start, and you move the cursor until you get a beginning of color dot then you stop.</p>

<p>BLACK/ you should get a white screen to start, and you move the cursor until you get a beginning of color dot then you stop.</p>

<p>For the black, on a well exposed normal shot, the *magic* number is many time around 3-4-5 in the box on the end of the cursor.</p>

<p> </p>

<p>If you roll the cursor over the histogram window (Photoshop), statistics at each location will be displayed in the table below. Data includes the tonal value (i.e., 250), the pixel count at that point and the percentile. 100% percentile means all pixels fall below that value, etc.</p>

<p>In the Levels tool (also an histogram), you can use the pointers to graphically see the pixel count at any point, and the output scale to force these limits to any value between 0 and 255.</p>

<p>Edward, i think the OP talk about ACR only as he seem to know that he can do it in Photoshop ; )</p>

 

<blockquote>

<p>"while editing, i would like to know that my RGB is between 4 to 250."</p>

</blockquote>

<p>I wouldn't limit the images at this early stage – think about blacks with no detail and specular highlights.<br /> If this is per request from a printer (CMYK), do it afterwards in PS using the eyedropper tool with those target values.</p>

<p>thank you very much everyone. this is very helpful. a stock agency i will be suplying photos to, does not was photos to get clipped. and i was wondering if they strictly want photos in those numbers or they are just a point of caution! <br>

i am new to editing and cannot understand the technique Martin is talking about. i am going to find out about using the eye dropper tool. <br>

thank you everyone once again. </p>

<p>i would follow the technique i explain earlier and stay away from the eye dropper tool for the rest of your digital life ; )</p>

<p>dont bother with CMYK, that will just complicated your life and stock agency rarely if never ask for this.. concentrate your effort learning how to correctly process your image in raw and in Adobe RGB (or else following the stock agency instruction).</p>

<p> </p>

<blockquote>

<p>i would like to know that my RGB is between 4 to 250...</p>

</blockquote>

<p>Why’s that? </p>

<p>Patrick,</p>

<p>That's not how I read the OP, given the "interesting" syntax. Perhaps it is the OP's responsibility to clarify his question if I miss his point?</p>

<p>The eyedropper in the Levels- or Curves dialogue is a powerful tool, that, if understood and used correctly, can help to eliminate a colour cast and remap areas to near-white and -black while still maintaining a minimum of detail at either end.<br>

It goes beyond what colour balance and setting a white- and black point do.</p>

<p>Quoting from the PS help:</p>

<blockquote>

<p>"You can use the eyedroppers in the Levels or Curves dialog boxes to correct a color cast—an unwanted tint from an excess of color (red, green, blue, or cyan, magenta, yellow). It’s easier to color-balance an image by first identifying an area that should be neutral and then removing the color cast from that area. Depending on the image, you may want to use one or all three of the eyedroppers. The eyedroppers work best on an image with easily identified neutrals."</p>

</blockquote>

<p>But as Andrew said, why would you want to do this in the first place?</p>

<p>Martin, the keyword is :<strong><em> The eyedroppers work best on an image with easily identified neutrals.</em> </strong></p>

<p>When you dont have such a easy reference, it work like s****, because what I consider a black point does not mean its the same that YOU consider a black point.. same with the white. The easiest way of finding a black and white point in a normal image without any easy reference is to use the ALT key when playing with the black and white cursor.. that way, you have a visual reference where the point are, keeping everything under control, meaning not blowing or blocking shadow.</p>

<p>As for the gray neutral eye dropper.. again, without a visual reference like a gray card it worth close to nothing to help you find a neutral gray.</p>

<p>I then dont agree with you when you said it goes beyond what color balance and setting the balck and white point do, because between you and me, it sound pretty similar ; )</p>

<p>believe me, in the Photoshop retouching and darkroom area i know a thing or two (im not perfect, but after 18years i can say im comfortable with it)</p>

<p> </p>

<p>I agree, that it can be tricky to use, especially if an image doesn't contain any neutrals.<br>

But the fact that you don't like it, doesn't make it a useless tool in general.</p>

<p>OK, i agree, its not that useless (even if i stop using it in version 4 personnaly) , but since most of the images people have dont have a easy findable black and white point nor a neutral one, by using the ALT method is then bullet proof for amateur and pro alike. if a method can give you perfect result in less than 8sec, anything else that take more time or need to rely on guess or complicated method is for ME useless ; )</p>

<p>eye dropper tool in that context, the sharpen, sharpen more, USM are for me a example of things i dont use since a long time because something better and faster exist... they are probably not useless, but not good enough for the result i want.</p>

<p>This is really starting to veer offtopic, but I’ve found saturation to be a very useful tool in

correcting gray balance when there’s no reliable neutral target in the scene, as well as in scenes

with mixed lighting.</p>

 

<p>Boost the saturation at least into “stun” range, and possibly all the way to

“kill.” Use your preferred method of adjusting gray balance; the ACR sliders are excellent.

When gray balance is correct, the picture will look overly saturated. When the gray balance is off by

even a little bit, the picture will look hideous.</p>

 

<p>Obviously, return the saturation back to normal once you’ve applied your corrections.</p>

 

<p>Cheers,</p>

 

<p>b&</p>

<p><em>...while editing, i would like to know that my RGB is between 4 to 250.</em></p>

<p>Get to Curves ( use adjustment layers)<br /> <br /> on the bottom left of diagram is "Input" and a black triangle. Click on it and hold and drag to the right until you see 4 or just enter 4 in the field box.</p>

<p>on the bottom right of diagram is a white triangle, click and hold and drag to the left until you see 250 or just enter 250 in the field box.</p>

<p>But I find it really easy to use the three eye droppers (black/neutral/white) in curves and do as Martin does.</p>

<p>Patrick,<br>

I don't debate the ALT key method you describe, because after all that's what I do too, to start with.</p>

<p>I realise, I might not have explained well enough earlier how I use they eyedropper.<br>

First the PS defaults aren't useful, so I set the sampling area from 1-pixel to e.g. 5 by 5. Then I adjust the target values of the white and black one to be slightly off-white and off-black by double-clicking. For instance instead of RGB 0/0/0 for black, I'd specify 8/8/8 and for the white 245/245/245 instead of 255/255/255.</p>

<p>In an image of e.g. a person wearing a white shirt, I can then click the brightest area of the fabric and make sure it will be neutral and still retain a bit of printable detail. Had I used the eyedropper with its default value, that area would be blown out – not the result I'm after. Same goes for the black.<br>

It's not about setting a 0% black or a 100% white, but defining areas of near-black and -white, where you want to preserve a minimum of detail.</p>

<p>then i agree with you ; )</p>

<p>Oh and boys, it must be my limited english comprehension, but from what i read the OP ask how to do this in ACR... is it just me or what?</p>

<p><em>edit</em> _ok after reading the sentence 20times the OP seem to ask how to do it in ACR and maybe in Photoshop also...</p>

I do what Martin suggests, however I go to Image - Adjustments - Treshhold in Photoshop to find my white and black areas.

<p>Ray, if you want to speed things up, just use the ALT key in the level .. without the eye dropper.. it doe exactly the same things as going in another filter to see where the points are, then use the eye dropper to get them.. same exact result, faster just to use the ALT.. so simple ; )</p>

<blockquote>

<p>to get that in Lr or ACR, simply press and hold the ALT key while at the same time using the exposition cursor ...<br>

WHITE/ you should get a black screen to start, and you move the cursor until you get a beginning of color dot then you stop.<br>

BLACK/ you should get a white screen to start, and you move the cursor until you get a beginning of color dot then you stop.</p>

</blockquote>

<p>Patrick, do you mean use "Exposure" and ALT for a black screen. "Blacks" and ALT for a white screen?</p>

<p>I've tried this a few times in the past and never cared for it. Maybe I'm doing it wrong, but I always seemed to go back and adjust the sliders. Maybe it's the lack of a preview, I don't know.</p>

<p> </p>

<p>yep.</p>

<p>it is the exact same thing as in level. you CANT go wrong with this method, because you dont have to guess about where you THINK the black point is or the white point is.. even if you have 0 knowledge anyone can do it.</p>

<p>when you have your image in Lr in th develop module, press and hold the ALT key, while at the same time get the cursor on the EXPOSURE, the screen should turn black, and when you move the slider (still holding the alt key) you will see some red or green color speckle..stop there, you just set you white point. Do the same with the alt key with the BLACK adjustment, screen will turn white, when you move the cursor while holding the alt, you will again see some color speckle.. stop there. voila, black and white point set and perfect.. simple and fast. I do this on all my file, like 50 time a week since decade (well decade in level, 3 years in Lr ; )</p>

<p>it is a powerfull tool that doestn relly on guessing, or setting, anyone in my workshop (real newbies) after 3min of explanation get this and are set to go on any images after this. When i explain them after how to work with eye dropper tool in Level, how to configurate them, how to use them.. all of them get different result with the same image?! when they go back to the ALT key they get similar result.. and they ask why i explain them the second *difficult* method LOL</p>

<p>Of course, its hard for anyone to get new way of doing things, but some are worthy of experiencing, and some new method are used by pro for a reason ; )</p>

<p>let me know if it work for you, then maybe after i will be able to convince you to get a mac.. you never know LOL</p>

<p>Mac? Lol, not this again. I've already been there. At least twice. Maybe I'll go back for a third. See if CS5 is 64 bit and build a Hackintosh for the hell of it. My gf/partner will kill me though.</p>

<p>I still prefer sliders without blacking out the screen, and previewing the results as I slide baby, slide.</p>

Thank you Patrick, will try that tonight!

<p>Hi Patrick<br>

I'm trying to follow your directions (above) and I'm lost. <br>

Holding down the Alt key and putting my cursor on the exposure slider. I understand that. But I'm not getting what you describe.<br>

Also, I dont understand how doing the same thing twice can give you two different results (one for black, one for white)... or I'm not doing it correctly. ?<br>

I've also tried putting the cursor on the Histogram (sliding each end, black and white) and doing the same thing with bewildering results.</p>

 

<p>tom, it's click and hold with mouse, then push ALT. Or hold ALT and click and drag the slider.</p>

<p>Use "exposure" slider for black and "blacks" sldier for white</p>

<p> </p>