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How do I find out what the black point/white point is
Hi Everyone,.

Hoping to submit some photos for stock, and the agency states that rgb values in photoshop should be limited to a white point of less than 248 and a black point no darker than 4..

How do I find out this information?.

Regards and thanks in advance.

Chris..

Comments (10)

Christ,.

Use Levels in Photoshop (Image > Adjustments > Levels)..

You should be able to read your present black and white points from the histogram in Levels. Move the input (upper) sliders so they point to the very ends of the graph (if they're not already there)..

Those points can be changed by using the output (lower) sliders. Move the left output slider to set your desired black point and the right output slider to set your desired white point. Then, click the OK button. That should do it. Rechecking the histogram in Levels should show that you have successfully corrected the black and white points..

See this page (link below) for info about the output sliders in Levels..

Http://www.zuberphotographics.com/content/photoshop/levels-output.htm.

Hope this helps,.

Bottles..

Comment #1

1. Open an image.2. Open the curves dialogue box by Apple M or (Control M).

3. At the bottom of the curves box there are 3 eyedroppers B-M-W (Blk, mid, white). Double click on the black eyedropper. the color picker opens with a row of boxes to the right. In the LEFT row ant the bottom vertically you will see R-G &B. Set each to "4" and click OK, You just set your black point to 4.5 Clicke on the white eyedropper and reset the RGB to 248-248-248 and click OK.You are done..

Van..

Comment #2

John p vansteenberg wrote:.

1. Open an image.2. Open the curves dialogue box by Apple M or (Control M)3. At the bottom of the curves box there are 3 eyedroppers B-M-W(Blk, mid, white). Double click on the black eyedropper. the colorpicker opens with a row of boxes to the right.

Set each to "4" and clickOK, You just set your black point to 4..

I'm not sure this is correct. I think what you have done is set the "target shadow color" to 4,4,4. When you subsequently single click the black/shadow dropper on a part of the image that you want to be black, it will be set to 4,4,4 instead of the default 0,0,0. IE, until you do the click on the image after setting the black target color, nothing is changed. It's kinda hard to see the difference between 0,0,0 and 4,4,4, so as a test, set the black target to something obvious, like 127,0,0. See if the black changes to red after you set the target.



5 Clicke on the white eyedropper and reset the RGB to 248-248-248 andclick OK..

White works the same way as the black..

However, I think the OP wants a different answer. I think the customer just wants an image that is properly exposed...ie, they don't want blown highlights or clipped shadows. The OP asked "How do I find out what the black point/white point is?".

One way is to use the Info Pallette...put the cursor on the whitest and blackest parts of an image and it will show the color values. You can also use the Eyedropper Tool to do this...click on a color, then double click on the foreground swatch in the lower-left...that will bring up the Select Foreground Color window...the color you clicked on will be shown..

There are also some statistical packages that tell you how many pixels of each color there are. And some editors (like LightRoom) will show you graphically the areas that are blown and clipped..

Charlie DavisNikon 5700, Sony R1, Nikon D300HomePage: http://www.1derful.infoBridge Blog: http://www.here-ugo.com/BridgeBlog/..

Comment #3

In addition hold down the Option(Mac) or Alt(pc) and as you drag the slider-.

When color starts to appear -you are beginning to blow out highlighs or losing shadow detail. Slide the slider on each end til color appears- then stop. that will set the point..

You can also use threshold and take color a sample of small area and set the points withe the eyedroppers in levels.If you need specific instructions on either technique let me know.Buzz..

Comment #4



Using cs2 or higher- it is no longer longer to set the shadow target poin to 4 -4- 4 Photoshop wiill automatically take the darkest area and make it a black.In the levels graph- just drag the slider to taste..

If you have cs3- there is no need to use levels at all Actually in earlier versions,I never used levels either, as curves are levels on steroids!!i do levels e it as a learning tool for beginners- before teaching curves..

Buzz..

Comment #5

I should photoshop will automatically make it black when PRINTED.Buzz..

Comment #6

Hi Chuck..

I think the reason for the specification is not for exposure at all, but it is to prevent clipped image files. It is really to be sure that the file does not exceed the upper and lower limits of the PRINTING (output media) system the client employs. Many prepress houses specify the 15-20 range for black and the 240-245 range for highlights..

What the process does do is to set the OUTPUT detail of the files black and white points, to 4 (or whatever). What is 0 on the file is moved to 4. Otherwise, the printer, with specific limitations for printing black an white would "block up" the shadows and highlights. It compresses the tonal ramp to fit inside an output capability so that ll the tones are preserved, not clipped. It presumes that YOU have already (either manually or through an automated function) set a full tonal range file, whatever the tones you include in the file..

It is separate from defining the black and white point with the eyedropper itself, which by forcing a shift, can induce both unnatural black point (clicking on a 90-90-90 setting in a low contrast fog scene forcing it to black, for example). It sets the terminal limits of the output range..

As to levels, which can make a similar adjustment, it is OK too, I choose the curves method because in working the numbers rather than the monitor, you eliminate system vaguaries between my system and the labs system. Nobody can argue who's monitor was mis-set. Also, it allows fine tuning an image with more options in one dialogue box, not multiple boxes..

John.

Chuxter wrote:.

John p vansteenberg wrote:.

1. Open an image.2. Open the curves dialogue box by Apple M or (Control M)3. At the bottom of the curves box there are 3 eyedroppers B-M-W(Blk, mid, white). Double click on the black eyedropper. the colorpicker opens with a row of boxes to the right.

Set each to "4" and clickOK, You just set your black point to 4..

I'm not sure this is correct. I think what you have done is set the"target shadow color" to 4,4,4. When you subsequently single clickthe black/shadow dropper on a part of the image that you want to beblack, it will be set to 4,4,4 instead of the default 0,0,0. IE,until you do the click on the image after setting the black targetcolor, nothing is changed. It's kinda hard to see the differencebetween 0,0,0 and 4,4,4, so as a test, set the black target tosomething obvious, like 127,0,0. See if the black changes to redafter you set the target.



5 Clicke on the white eyedropper and reset the RGB to 248-248-248 andclick OK..

White works the same way as the black..

However, I think the OP wants a different answer. I think thecustomer just wants an image that is properly exposed...ie, theydon't want blown highlights or clipped shadows. The OP asked "How doI find out what the black point/white point is?".

One way is to use the Info Pallette...put the cursor on the whitestand blackest parts of an image and it will show the color values. Youcan also use the Eyedropper Tool to do this...click on a color, thendouble click on the foreground swatch in the lower-left...that willbring up the Select Foreground Color window...the color you clickedon will be shown..

There are also some statistical packages that tell you how manypixels of each color there are. And some editors (like LightRoom)will show you graphically the areas that are blown and clipped..

Charlie DavisNikon 5700, Sony R1, Nikon D300HomePage: http://www.1derful.infoBridge Blog: http://www.here-ugo.com/BridgeBlog/.

Van..

Comment #7

I agree that this does not answer the how do I find part. Should have referenced either the threshold slider and/or Info pallet choices for that. Thanks for the refocusVan..

Comment #8

Hi Again,.

Thanks for so many replies - I've only just had chance to get on computer again. I'll have to have a good read of your replies, it all sounds very technical..

Just to re-iterate unless there is any confusion to what the stock library have asked for.

Highlights/shadows - We do not want to see highlights blown out or shadows filling in (RGB values in Adobe photoshop should be limited to a white point of less than 248 and a black point no darker than 4..

Hope this clarifies the info I need - I only have photoshop elements 2, do I need to upgrade my software to find out this information and if so which would be the best package..

Thanks in advance.

Chris..

Comment #9

Zzzz wrote:.

Hi Again,Thanks for so many replies - I've only just had chance to get oncomputer again. I'll have to have a good read of your replies, it allsounds very technical..

Just to re-iterate unless there is any confusion to what the stocklibrary have asked for.

Highlights/shadows - We do not want to see highlights blown out orshadows filling in (RGB values in Adobe photoshop should be limitedto a white point of less than 248 and a black point no darker than 4..

Hope this clarifies the info I need - I only have photoshop elements2, do I need to upgrade my software to find out this information andif so which would be the best package..

You might upgrade to PSE6...it's currently $50 at Costco!.

But PSE2 can do what you need..

Charlie DavisNikon 5700, Sony R1, Nikon D300HomePage: http://www.1derful.infoBridge Blog: http://www.here-ugo.com/BridgeBlog/..

Comment #10

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