are histograms logarithmically displayed? (relevant for expose to the right)

[snowbear]

(hence why RGB 127, 127, 127 is 18% grey, not 50%)?

I am pretty sure the percentage in 18% grey (ie - the grey card) refers to reflectivity; the value is simply "mid grey."

 

[fjrabon]

(hence why RGB 127, 127, 127 is 18% grey, not 50%)?

I am pretty sure the percentage in 18% grey (ie - the grey card) refers to reflectance; the value is simply "mid grey."

right, that a reflection of 18% of pure white light is "middle" is a result of our eyes seeing in essentially a logarithmic manner. And thus why we gamma correct the sensor's linear electrical response, so that it matches how our eyes see things.

 

[snowbear]

But the R127, G127, B127 refers to the value (lightness to darkness) of the grey hue = 50%

 

[spacediver]

Indispensable: RawDigger Raw Image Analyzer RawDigger

Nice, I do essentially the same thing using dcraw and then Matlab. Tricky part was figuring out the layout of the bayer array so I knew which photosites corresponded to which channel. If anyone wants the code, let me know. It'd probably carry over to Octave fairly well (Octave is free).

 

[spacediver]

But the R127, G127, B127 refers to the value (lightness to darkness) of the grey hue = 50%

lightness in this context is an approximately perceptually uniform representation of luminance. If you were to layout 100 adjacent patches, and fired photons at each patch, with a rate proportional to the patch number (so patch 10 would receive, say 1 billion photons per second, and patch 20 would receive 2 billion photons per second), the halfway point in terms of luminance would be patch 50. But perceptually, the halfway point would be around patch 18.

 

[unpopular]

Good old GIMP.

Joe

Photoline also has log histogram. And it has the added benefit in that doesn't suck.

Which is a plus.

 

[Ysarex]

Good old GIMP.

Joe

Photoline also has log histogram. And it has the added benefit in that doesn't suck.

Which is a plus.

I've spent some time with Photoline and it has some very attractive capabilities. It could function as a Photoshop alternative but the UI is difficult. If it had better masking control I'd be tempted to put in the effort to get used to it.

Joe

 

[480sparky]

View attachment 99538

Good old GIMP.

Joe

Oh, puh-leeeze. We all know GIMP does nothing more than display images.

Next, you're gonna tell us it can rotate & crop images.

 

[unpopular]

Good old GIMP.

Joe

Photoline also has log histogram. And it has the added benefit in that doesn't suck.

Which is a plus.

I've spent some time with Photoline and it has some very attractive capabilities. It could function as a Photoshop alternative but the UI is difficult. If it had better masking control I'd be tempted to put in the effort to get used to it.

Joe

UI is definitely weird, but I really do like it a lot. Never had too much trouble with masking, but my masking techniques are pretty "old school" - or were, until I started using Photoshop CC.