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 / a7RIII / a7RII superhot pixel frame-to-frame consistency

a7RII superhot pixel frame-to-frame consistency

November 27, 2017 JimK Leave a Comment

This is the ninth in a series of posts on the Sony a7RIII (and a7RII, for comparison) spatial processing that is invoked when you use a shutter speed of longer than 3.2 seconds. The series starts here.

Bill Claff, who I greatly respect, commented on yesterday’s post to the effect that he would look at a more stringent definition of hot pixels than the 5-sigma that I used. 

I reran the analysis of the 16-exposure a7RII 3.2 second series with a 10 standard deviation (10 sigma) threshold for qualifying as a hot pixel. 

Of the 10,000 or so hot pixels observed in all 16 exposures, less than 200 occurred in the same place in all 16. 

Steeping the criterion up to 20 sigma:

Now we have about the same number of hot pixels that occur in all 16 captures; the higher threshold has not eliminated many of them. But it’s cut way down on the less consistent hot pixels. 

If we go all the way to 30 sigma:

Not much difference. 

Now let’s look at a 4-second exposure with the same criterion for hotness:

There is no location that was hot for all sixteen images. There is one that was hot for 4 of them and 4 more that were hot in only one capture. The Sony hot-pixel suppression algorithm is suppressing quite well. If it weren’t for the astrophotographic side effect, we might be jumping up and down and cheering, although I still think these things should be done in postproduction.

What if we do pairwise subtraction on the 3.2-second series to emulate LENR?

That eliminates all the hot pixels that appear the same place in all 16 images. 

Since the number of fixed hot pixels is so low here — less than 200 out of eleven million — you might say that we have, by narrowing the definition so far, gotten more nearly the expected results, but results that are only marginally relevant to most real photography.  

 

 

a7RIII

← a7RII hot pixel frame-to-frame consistency Sigma 135/1.8 LoCA on D850 →

Leave a Reply Cancel reply

Your email address will not be published.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

March 2023
S M T W T F S
 1234
567891011
12131415161718
19202122232425
262728293031  
« Jan    

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

  • JimK on Sony 135 STF on GFX-50R, sharpness
  • K on Sony 135 STF on GFX-50R, sharpness
  • 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?

Archives

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

Unless otherwise noted, all images copyright Jim Kasson.