A different approach to scanned image histograms

[Taija71A]

No problem Neil. Understood in full.
Thank-you, for your update to the Thread.

-Tim.

[Struan Gray]

'Take a look at my excellent WFM plot' doesn't exactly trip of the tongue. 'Waveform plot' is easier to say. If they can stick with antiquated tube nomenclature for imaging chip sizes, the industry can probably cope with that.

I've been trying to find ways of efficiently preserving subtle colour in scans and direct digital capture. Scanner software and most raw developers (and built-in jpeg engines) push saturation and contrast too hard for my liking. A tool like this would make it easier to assess the best parameters for scanning or capture. I know it's available in hardware for some add-on monitors for DSLR filming, but not for most scanning packages.

Are you using plain Python, or also one of the add-on image processing or numerical packages?

[barnacle]

Plain python 3.4, GTK+ toolkit. Might actually be easier in 2.7, as there is more functionality in the GTK port at the moment.

http://www.dnbprojects.co.uk/python/image.py
http://www.dnbprojects.co.uk/python/image2.glade

Please bear in mind that this is very much unfinished, just a proof of concept, and very much remains to do to tidy things up. Like, e.g., not having everything happen in the response from the file select menu...

Neil

[Struan Gray]

Thanks Neil. I do various tinkering things with an old license for an image processing package (IDL), but it's not worth the substantial cost of an upgrade. Looking for options, ideally open source, as all the commercial vendors seems to be trying to lock their users into rent-rack agreements.

*All* my programs have dangling live wires. All the users (me) just know not to go licking them :-)

[BetterSense]

Thank you for the interesting post. I did not know such a thing existed.

Also, props for running Linux. I agree 100% that we all need to consider alternatives to Windows as their recent policies, not to mention quality of the product itself, has me very turned off. With Steam offering many videogames on Linux, I hope more vendors consider supporting Linux workstations.

[barnacle]

"wuffum"?

Thing is, is it really a waveform? It is on a linear TV signal, and it's generated as if it were the same, but... how about 'luma plot'?

Neil

[Struan Gray]

Luma won't really work: the video whippersnappers have no respect for tradition, and work with separate red, green and blue wuffums for each channel - on a colour display the individual wuffums can be overlaid without too much confusion, and it is possible to show only one of them.

I called them 'line scans' or, more accurately, 'line scan histograms'. In microscopy (my field was STM) you often rotate to an arbitrary angle to align with surface features, so it was always explicit that you were extracting histograms perpendicular to a given direction. 'LSH' rolls off the tongue a bit easer than 'WFM', but 'wuffum' is pure genius, and is growing on me :-)

[barnacle]

An alternative (better?) display brightness function - where the brightness is summed at line 64 and following, replace with


# we increment the brightness by some part of the difference between its current level and peak
b = 256 - brightness[brightptr]
brightness[brightptr] += int(b/4)

This restricts the brightness range but emphasises the less bright parts; divisors of 2, 3, and 4 work well. This image has a divisor of 4.



Neil

[Struan Gray]

Log works pretty well for bringing up the floor, if you can live with the calculation time/memory.

[stawastawa]

a glance at this wuffum and i might be concerned I had clipped the window.

The examples in the video tutorial seem to be easy to read and correlate to the images - what brightness scaling are they doing?

the 100% brightness examples posted earlier were to harsh. a divisor of 4 seems not strong enough. IMO

very interesting data visualizer!

An alternative (better?) display brightness function - where the brightness is summed at line 64 and following, replace with


# we increment the brightness by some part of the difference between its current level and peak
b = 256 - brightness[brightptr]
brightness[brightptr] += int(b/4)

This restricts the brightness range but emphasises the less bright parts; divisors of 2, 3, and 4 work well. This image has a divisor of 4.



Neil