• site home
  • blog home
  • galleries
  • contact
  • underwater
  • the bleeding edge

the last word

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

You are here: Home / The Last Word / Adding a dc component to autohalftoning kernels

Adding a dc component to autohalftoning kernels

April 3, 2014 JimK Leave a Comment

In addition to kernel size and construction, you can also get useful effects by making the kernel sum to numbers slightly larger than one. This means that the kernel is not strictly a highpass filter, but will preserve some low frequency information. You don’t want much; multiplying the center element of a fence kernel by 1.01 to 1.10 seems to be the sweet spot, but you can have a great deal of control over the look of your image this way.

If you’re into weirdness, you can make the center entry slightly smaller than one, which gives an effect reminiscent of a photographic negative.

I wrote a little Matlab code to tweak the kernel center value.

adjustCenter

And here’s what it looks like applied in varying amounts to an image:

fs-1fenceBottom13clipoffsetp05thrp0kc1ClipHighmpy108

fs-1fenceBottom13clipoffsetp05thrp0kc1ClipHighmpy102

fs-1fenceBottom13clipoffsetp05thrp0kc1ClipHighmpy105

 

 

 

The Last Word

← Fence kernels for autohalftoning Making sidecar files →

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

July 2025
S M T W T F S
 12345
6789101112
13141516171819
20212223242526
2728293031  
« Jun    

Articles

  • About
    • Patents and papers about color
    • Who am I?
  • How to…
    • Backing up photographic images
    • How to change email providers
    • How to shoot slanted edge images for me
  • 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 35-70 MF 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

  • Michael Angelo on Nikon Z7 focus shift shooting
  • Erik Kaffehr on Visualizing lens aberrations — why do it?
  • Eugene on Don’t fixate on the bad stuff
  • Jonby on How focus-bracketing systems work
  • JimK on Of fidelity, photography, audio, and wine
  • JimK on Of fidelity, photography, audio, and wine
  • AVN on Of fidelity, photography, audio, and wine
  • Markus on In photography, and in life, work and joy can, and should, coexist
  • JimK on Fuji 120/4 GF at 1:1 with tubes — visuals
  • Christopher Roberton on Fuji 120/4 GF at 1:1 with tubes — visuals

Archives

Copyright © 2025 · Daily Dish Pro On Genesis Framework · WordPress · Log in

Unless otherwise noted, all images copyright Jim Kasson.