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the last word

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

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Luminance and chromaticity vs spatial frequency

April 20, 2014 JimK Leave a Comment

There was a great thread on the dpreview forum started by Jack Hogan (who has also posted in this blog), about anisotropy in anti-aliasing filters. In the generally erudite and productive discussion that followed, someone (I’d give him credit, but I don’t know his real name) made these comments about demosacing: From a reconstruction perspective,… [Read More]

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Color photography without demosaicing in the real world

April 19, 2014 JimK 4 Comments

Today I continue exploring using a technique to produce half-sized images from sensors with Bayer color filter arrays (CFAs). The technique was described here, and the way I’m implementing it was explained here. I started with a raw file of this scene, photographed with the Sony a7R and the Sony/Zeiss 55mm f/1.8 Sonnar FE (aka… [Read More]

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Color photography without demosaicing in practice

April 18, 2014 JimK Leave a Comment

Yesterday’s post trotted out an idea for producing moderate resolution files from high-resolution cameras without demosaicing, and speculated that such files might show higher quality and fewer artifacts than similar-sized filed down-res’d from demosaiced raw files. I looked around for a tool to perform an experiment. I didn’t have to look far. DCRAW has an… [Read More]

The Last Word

Color photography without demosaicing

April 17, 2014 JimK Leave a Comment

In the beginning, digital photography sensors were monochromatic. If you wanted color, you made three successive exposures through different filters, which were usually mounted on a wheel for rapid sequencing. A variant of this approach was to use a series of prisms and half-silvered mirrors to split the imaging light into three beams which were… [Read More]

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The Pentax 645Z

April 16, 2014 JimK 4 Comments

There have been rumblings for months about a new Pentax 645 based on the Sony 50MP 33x44mm chip that’s in the Phase One IQ250 and the Hasselblad H5D-50c. The buzz was that it would be cheap (for a medium format camera) and that Ricoh would put some marketing, service, and distribution wood behind the camera… [Read More]

The Last Word

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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

  • JimK on Goldilocks and the three flashes
  • DC Wedding Photographer on Goldilocks and the three flashes
  • Wedding Photographer in DC on The 16-Bit Fallacy: Why More Isn’t Always Better in Medium Format Cameras
  • JimK on Fujifilm GFX 100S II precision
  • Renjie Zhu on Fujifilm GFX 100S II precision
  • JimK on Fuji 20-35/4 landscape field curvature at 23mm vs 23/4 GF
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  • JimK on Fuji 20-35/4 landscape field curvature at 23mm vs 23/4 GF
  • JimK on Fuji 20-35/4 landscape field curvature at 23mm vs 23/4 GF
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Unless otherwise noted, all images copyright Jim Kasson.