the last word

Photography meets digital computer technology. Photography wins -- most of the time.

  • site home
  • blog home
  • galleries
  • contact
  • underwater
  • the bleeding edge
You are here: Home / 2014 / Archives for April 2014

Archives for April 2014

Contrast Sensitivity Functions and Photography

April 30, 2014 JimK 1 Comment

Let’s look first at the drop in luminance contrast sensitivity at low spatial frequencies. That’s why dodging and burning works. Slow changes in luminance are introduced by the printer (in the old days) or editor (now) so that local contrast can be higher or to call attention to or from image elements. Done right, the… [Read More]

The Last Word

Chromaticity Contrast Sensitivity Functions

April 28, 2014 JimK Leave a Comment

Yesterday, I presented material on how people’s ability to perceive small – and not so small – luminance changes varies with spatial frequency. Today, I’ll talk about how our ability to perceive changes in chromaticity (color without luminance) varies as spatial frequencies are manipulated. Yesterday, I started with the graphs and followed up with the… [Read More]

The Last Word

Contrast sensitivity vs spatial frequency

April 27, 2014 JimK Leave a Comment

We’ve seen that the sensitivity to luminance variation falls off as the luminance spatial frequency increases. If turns out that it also falls off as spatial frequency decreases, giving a band-pass filter effect, which sharpens edges, and gives rise to the Mach Banding that we’ve been looking at in the preceding posts. There are many… [Read More]

The Last Word

Looking for Mach Bands in chromaticity step wedges

April 25, 2014 JimK Leave a Comment

I reworked the luminance step wedge of yesterday’ post so that it consists of 10 Delta-E steps from zero to 80 along the gray (a* = 0, b* = 0) axis: The Mach Bands are evident. Then I created a similar image, with L* = 50, b* = 0, and a* starting at -40 and… [Read More]

The Last Word

Mach banding

April 24, 2014 JimK 1 Comment

Inspired by the last three posts, I’m starting a series of posts on spatial considerations in color vision, which an emphasis on what’s important to photographers. We’ll get started today with an illustration: Take good look at this image from a normal viewing distance: The bars are even steps along the grey axis in a… [Read More]

The Last Word

  • 1
  • 2
  • 3
  • 4
  • Next Page »
April 2014
S M T W T F S
 12345
6789101112
13141516171819
20212223242526
27282930  
« Mar   May »

Articles

  • About
    • Patents and papers about color
    • Who am I?
  • Good 35-70 MF lens
  • How to…
    • Backing up photographic images
    • How to change email providers
  • Lens screening testing
    • Equipment and Software
    • Examples
      • Bad and OK 200-600 at 600
      • Excellent 180-400 zoom
      • Fair 14-30mm zoom
      • Good 100-200 mm MF zoom
      • Good 100-400 zoom
      • Good 100mm lens on P1 P45+
      • Good 120mm MF lens
      • Good 18mm FF lens
      • Good 24-105 mm FF lens
      • Good 24-70 FF zoom
      • Good 35 mm FF lens
      • Good 60 mm lens on IQ3-100
      • Good 63 mm MF lens
      • Good 65 mm FF lens
      • Good 85 mm FF lens
      • Good and bad 25mm FF lenses
      • Good zoom at 24 mm
      • Marginal 18mm lens
      • Marginal 35mm FF lens
      • Mildly problematic 55 mm FF lens
      • OK 16-35mm zoom
      • OK 60mm lens on P1 P45+
      • OK Sony 600mm f/4
      • Pretty good 16-35 FF zoom
      • Pretty good 90mm FF lens
      • Problematic 400 mm FF lens
      • Tilted 20 mm f/1.8 FF lens
      • Tilted 30 mm MF lens
      • Tilted 50 mm FF lens
      • Two 15mm FF lenses
    • Found a problem – now what?
    • Goals for this test
    • Minimum target distances
      • MFT
      • APS-C
      • Full frame
      • Small medium format
    • Printable Siemens Star targets
    • Target size on sensor
      • MFT
      • APS-C
      • Full frame
      • Small medium format
    • Test instructions — postproduction
    • Test instructions — reading the images
    • Test instructions – capture
    • Theory of the test
    • What’s wrong with conventional lens screening?
  • Previsualization heresy
  • Privacy Policy
  • Recommended photographic web sites
  • Using in-camera histograms for ETTR
    • Acknowledgments
    • Why ETTR?
    • Normal in-camera histograms
    • Image processing for in-camera histograms
    • Making the in-camera histogram closely represent the raw histogram
    • Shortcuts to UniWB
    • Preparing for monitor-based UniWB
    • A one-step UniWB procedure
    • The math behind the one-step method
    • Iteration using Newton’s Method

Category List

Recent Comments

  • Mal Paso on Christmas tree light bokeh with the XCD 38V on the X2D
  • Sebastian on More on tilted adapters
  • JimK on On microlens size in the GFX 100 and GFX 50R/S
  • Kyle Krug on On microlens size in the GFX 100 and GFX 50R/S
  • JimK on Hasselblad X2D electronic shutter scan time
  • Jake on Hasselblad X2D electronic shutter scan time
  • Piotr Chylarecki on Who am I?
  • JimK on Who am I?
  • Piotr Chylarecki on Who am I?
  • Stefan on Swebo TC-1 OOBE

Archives

Copyright © 2023 · Daily Dish Pro On Genesis Framework · WordPress · Log in

Unless otherwise noted, all images copyright Jim Kasson.