Gradation curve and Histogram

[norris_watkins]

( Im using Silverfast Plus 8.0 on an Epson v700 scanner )
1. What exactly is being shown on the histogram ( Is it teh input or teh output after applying all teh settings.
If its the input, then nothing we do should have an effect on teh histogram ( Assuming that Silverfast does not change the actual scanner exposure as a result of changing any settings )
If it is the output - after applying the settings like AACO - then it shoudl change against things like AACO, shadow/highlight sliders etc

2. Why doesnt teh gradation curve change when AACO is enabled ? ( AACO amplifies the shadows correct ? ) ( Isnt AACO same as Gamma ? )

[LSI_Morales]

Hi norris

It is the input histogram

If its the input, then nothing we do should have an effect on teh histogram ( Assuming that Silverfast does not change the actual scanner exposure as a result of changing any settings )

Not completely true, actually the content of the scan frame determines the info in histogram, if you change the scan frame or choose a different part of the image or a completely different scan frame, then the histogram will be different.

SilverFast Ai Studio has an output histogram.

2. Why doesnt teh gradation curve change when AACO is enabled ? ( AACO amplifies the shadows correct ? ) ( Isnt AACO same as Gamma ? )

Because they are two separate filters.

Cheers

[norris_watkins]

Thank you Morales :
So what is being shown in Histogram is the Input Histogram correct ?
The Gradation curve seems to be acting as a 'Transfer curve' ( the curve that defines the relationship between input and output ).
But then settings changes like AACO ( which boosts the shadows ) does not have any effect on Gradation curve.
( Setting AACO should have boosted the lower part of teh curve, if it were acting as a Transfer curve )
Similarly changing Shadow point and Highlight point also do not have any effect.
( changing them from 0 and 255 should have respectively made the curve stick to teh lower and upper limits )

So it is not a curve that defines teh relationship between Input and Output.
If true, then what it Gradation curve ? ( what are its X axis and Y axis ? )

[LSI_Morales]

Hi there,

Think of those filters as being in different layers (the gradation curve as well), that is the reason why those changes are not reflected in the gradation curve.

Kind regards