Digital BW, The Print

Jason,

I don't disagree with anything you are saying, but I mean that even in in an
analog scenario, contrast and density reveals inherent flaws.

So, assuming my experiment is a flawed one, how else might one test to
determine if what they don't like in their image is a function of a broken
histogram, vs, bad data, which is merely being exposed as such?

Todd

> Increasing contrast (which I find is what I'm doing most of the time) is the
> thing that kills the histogram, because you are stretching a smaller range
> of values into a larger range. Decreasing contrast shouldn't really cause
> any problems. Here's an easy experiment that illustrates it: open a new
> blank image in Photoshop and use the gradient tool to create a gradient from
> pure black to pure white across the image. The histogram should be
> relatively smooth. Now use the levels tool to reduce the contrast so the
> gradient goes from, say, 60% gray to 40% gray. The histogram will be
> squashed into the middle, but should still be as smooth as before. Now use
> the levels again to reverse it back to a black to white gradient. The
> histogram will have huge gaps, and there should be obvious banding in the
> image.
> 
> Of course, as others have said, all this histogram worship has been a bit
> overblown. It all depends on the image. Not all images will have smooth
> histograms -- an image of black and white stripes for instance -- and the
> only thing that really matters is how the print looks. That being said,
> getting a handle on the principles at work has finally helped me understand
> why I was getting posterization in some of my images, and switching to a
> 16bit workflow has helped me solve those problems.
> 
> -Jason
> 
> -----Original Message-----
> From: Todd Flashner [mailto:tflash@...]
> Sent: Tuesday, August 14, 2001 1:55 PM
> To: DigitalBlackandWhiteThePrint@yahoogroups.com
> Subject: Re: [Digital BW] Re: Image Histograms Destroyed
> 
> I assume when you fatigue the the shy it's is through darkening
> it, and/or adding contrast. This always seems to expose defects in film and
> scans for me. If you were to apply an equal move in the opposite direction
> instead, i.e., lightening it how would it look? Heck, lets really test
> it....