|Standard:||ISO 21550 — Photography— Electronic scanners for photographic images — Dynamic range measurements|
|Technical Committee:||ISO/TC 42 Photography|
This tiny ISO 21550 chart for measuring dynamic range, printed on 35mm film and available from the Imatest Store, can be analyzed using the Special (Multi-row) charts “general mxn“ option in Multicharts (highly interactive UI) or Multitest (batch-capable fixed UI).
Since the chart patches are not in a standard numbering order, we had to apply a bit of cleverness to create density reference files for the two versions of the chart (0-4 and 0-6 OD). We copied the density values from the Technical Information tab on Edmund’s page, pasted them into an Excel spreadsheet, added a column where we manually entered the Imatest patch numbers, sorted the data, then wrote the two CSV reference files), which can be downloaded by clicking on the links below.
ISO-21550_0-4_reference (reference file for 0-4 Optical Density)
ISO-21550_0-6_reference (reference file for 0-6 Optical Density)
To test this we modified the Edmund image to have more reasonable patch values, Then we ran the image. Click on the thumbnail on the right to download it.
Then open Multicharts and select 7. Multi-row Grayscale & Color charts or Multitest, press the Setup button to the right of the Multitest window and make the same selection.
Then, make the following selections in the Multicharts Special Chart selection window (prior to Imatest 5.2). In Reference source, enter Density file (if the reference file has not yet been selected); you will be asked to enter the file later. (In Multicharts you can enter a density file at any time.)
Multicharts Special Chart selection window (pre-Imatest 5.2)
Here is a plot showing density response and noise. The lower plot had to be cropped slightly to remove some anomalous SNR values.
Many types of noise, SNR, and Dynamic Range can be displayed using the the dropdown menu below Settings (set here to 15. Scene-referenced SNR dB). See Color/Tone/eSFR ISO Noise for details.