trouble getting smooth darks

SusanV

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Jul 10, 2004
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Hi guys,

This is a problem I've had for a long time, whether using film and scanning it,
or now with my digital slr. When I open the image in ps, the last few steps
of my darks aren't smoothly gradated. I just have solid areas of black that,
along the edges make a big jump in value. I can post an image if need be,
but I thought this might just be a simple fix, where my error is something
obvious (except of course, to me ) )

help please,
susan
 

Ben Altman

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Susan, I assume you've checked your monitor? - Make an all-black file, then select an area and lighten it one level at a time with a curves layer to see how far you have to go to see a difference.

Otherwise it sounds like some kind of posterization - could be to do with the working space you use or the embedded profile of your files? Experiment with a large-gamut working space, maybe.

That's about all I know...

Ben
 
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SusanV

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Jul 10, 2004
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Bob... uploaded and emailed, thanks.

Ben.. thanks, I re-calibrated my monitor with my XRite eye1 display 2, but it
was in good shape. Then I did the test you recommended. I start to see the
selection box at level 8 or so. If I didn't know what I was looking for, it would
be more like 10 from viewing distance (24 inch monitor).

Anyway, I never thought of doing that and it brings up a good point. Is that a
respectable result? I have a 3 year old Dell 24" monitor that is/was their top of
the line at the time and had good reviews for graphics.

susan

oh... and I'm using Adobe RGB color space and converting to black and white
in Adobe Bridge. 16 bit grayscale.
 
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Bob Carnie

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Hi Susan
I just lost my reply to you which actually was quite intensive and not sure how I lost it.
Basically a couple of problems

File size is small
Red Channel good
Green Channel not bad
Blue Channel a mess

Your conversion technique should be one that gets rid of the blue for sure.
You should do this first before any work in adjustments is done otherwise you will be magnifiying an already looming problem.

You may need to do some noise reduction , blurring locally to fix some of the noise after a safe conversion is done.

I believe working in channels for the conversion and apply image, with some curve shaping on the red channel then mode change to greyscale.

I will walk you through your image **for the second time ** damm but right now I have to go .

But in this image case the Blue Channel is a ugly monster.


regards
Bob


 
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SusanV

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Jul 10, 2004
Messages
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Medium Format
Bob,.... grrrr so sorry about the lost reply, that stinks. "No good deed goes
unpunished".

What you said though, is a huge help and a place to start. I'll look at those
channels and see what I can do there.

thanks!!!!!!
susan
 

Bob Carnie

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Susan

When I get a moment over the next week I will do a detailed post or thread that outlines my workflow for BW conversion from colour file.
then maybe some of the good workers will jump on board and give up any of their methods for conversion.
I will use your image as a reference so you can work through with the post and see if it makes any difference for you.

I have found the Channel Pallette and Info LAB pallete two of the most helpful methods of checking work in Colour and Black & White.
Also a second monitor ** crappy monitors for tools and pallettes is OK** is the way I work and recommend, the good monitor for the image , secondary for the tools.

Bob
QUOTE=SusanV;12253]Bob,.... grrrr so sorry about the lost reply, that stinks. "No good deed goes
unpunished".

What you said though, is a huge help and a place to start. I'll look at those
channels and see what I can do there.

thanks!!!!!!
susan[/QUOTE]
 

Ben Altman

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Location
Ithaca, NY a
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Hi Susuan,

Level 10 to see the difference is pretty crappy, I'd say. I checked my CRT Sony GDM C520, which is getting a bit long in the tooth; I could see the difference pretty easily at level 2 - and I profile the monitor darker than standard. I remember trying this on a friend's Apple cinema display (20" I think) and it was easy to see level 1. Perhaps you could find someone nearby with a fancy monitor and take a look at a couple of your files?

I wonder also what you can discriminate once the monitor starts registering. Another brutal test is to split a blank file in half horizontally across the screen and make a 100% Photoshop gradient on each half, one going left to right and one right to left. Then look to see if the gradient is even or has lines and bumps. You could also make a test file with squares at one per level for the first 30 levels or so and see what you can read.

I'm no expert on color space but Adobe is pretty standard. You could try taking a look at the histogram of each channel and then assigning ProPhoto RGB, which is a big space, I think, for comparison.

Ben
 

Bob Carnie

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Susan V

There is a thread on Large Format about conversion to black and white, that you may want to follow. I went through the steps there on how I like to convert and maybe it will help you.

There is also other comments and methods posted and any one of them may be suited for your needs.

Bob
 
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