Dragonstar made a nice comment about my latest (April 2) The Weekend in Black and White contribution: Trees: Tone & Texture — Ceres 2010. “One day I must try to understand what you do with your negatives…” Margaret Gosden is also interested and I’ve been meaning to write a few new tutorials (it’s been too long), so…
I decided to kick off the series with an introduction that recreates the sequence of steps I took to improve the tonality of the scanned negative prior to sharpening. The illustrations are screenshots from Picture Window Pro. Click to enlarge so you can see the details.
The image on the left is a medium resolution (1410 dpi)16 bit scan I made using VueScan with my Minolta Scan Dual III film scanner. I did some preliminary rough tonal adjustments using curves in VueScan. I did the fine tuning with PWP.
You can see the histogram and my adjusted curve in the Brightness Curve dialog in the middle of the screen. I felt the shadows needed some darkening and the overall image a contrast boost.
This screen shows the same before and after images with the alternate view of the Brightness Curve dialog. It’s easier to see the curve I applied.
The dialog shows the existing histogram on top and the new histogram on the bottom. I established two control points using the double headed arrows, one for the shadows and another for the highlights. I moved the bottom of the shadow arrow to the left and the highlight arrow to the right.
The new curve is superimposed on the histogram display. The image on the right is the result. It doesn’t take much to make big changes. As you can see, I moved the shadows just enough. I anchored the highlights and boosted them the tiniest bit. If I hadn’t anchored the highlights, the entire curve would have been pulled down.
The result is a steeper curve which increases contrast, deeper shadows and a wee boost to the highlights.
Here’s where I applied a bit of local contrast enhancement. The unsharp mask dialog shows Amount = 10% / Radius = 30 / Threshold = 0, very conservative settings. Some people use amounts of 20% or more and radii of 50, 60 or more. I use higher settings sometimes depending on the image.
Local Contrast Enhancement (LCE) can work magic on some images. I use it all the time now. Rather than try to explain how LCE works, here’s a link to a good tutorial on the subject.
The next few steps (final sharpening and size reduction for the web) were done using Gimp. The Gimp can’t handle 16 bit files so I converted and did a save as 8 bit (different file name) and opened the file in the Gimp. I sharpened this image using smart sharpening. I’ll get into different sharpening methods in another tutorial.
Think of this article as more introduction than full blown tutorial. Next time I’ll get into more details.