Dynamic range controls &c.

[rfuerman]

Hello.
PW 8.0.384
Transformation | gray | auto range
a) definition: Dynamic Range seems to be defined as "the difference between the lightest and darkest tones in a photograph.." The PW 'Curves & histogram' pdf says use the black and white points on X-axis to adjust black point & white points.
b) Auto Range transform | Dynamic Range control. Move the control arrows moves the curve endpoints up or down to adjust what? Shouldn't it move end points in or out to adjust dynamic range?
c) User turns off {x] auto black or [x] auto white, then there is no way to manually adjust black or white endpoint. The control arrows on X-axis are display only. Why would user turn these off if transform expects auto range?
d) Help for Auto Range transform says to use histogram mode button, but this button is not available. Shouldn't all buttons be available, esp temporary reset?
e) the black & white threshold settings are used to exclude outlier black or white pixels for HSV. If I select color space = RGB, I don't expect outlier color pixels so how are threshold adjustments helpful?
f) Compare: Color curve transform remembers each setting for RGB=R,G or B. Auto range transform keeps same endpoint setting for all channels.

(A) I'm thinking that this transform should always be auto for dynamic range endpoints. Only edits available to select color space and set thresholds. Otherwise its a limited version of Color Curves transform, Or ..
Add a button to Color Curves transform to [auto calc] which sets dynamic range endpoints for R,G,B or selected color space; button then becomes not available. User then can edit as desired. If user resets or changes color space, then button is available. I frequently set endpoints for the R,G,B channels, so if PW could auto calc them, that would be big help.
Put the 'Threshold' settings on [Settings] button of Color Curves - how often will they really change?
You now can remove this auto range transform?
**Note that help for the Curve Control settings menu includes 'Auto range' menu item, but this item is *not* on the settings menu for color curves! I suggest this should be added to Color Curves as a button, as above, and not hidden on settings.

Transform | Levels & Color
g) Help for Dynamic Range white point slider says "The effect depends considerably on the color space you have selected (see above)." But this transform does not allow user to select color space. Whoa! I see color space control at *bottom* of transform - that needs to move up to above the Dynamic Range control?
h) the help for Levels & Color transform has two descriptions of the Saturation control.

Color Space
i) Color Curve transform Color Space control allows user to select 'HSV' space and then specify channel 'H, S or V'. The Levels & Color and Auto Range transforms do *not* allow user to select 'H, S or V'. Suggest adding this channel control, not available, so user knows which color space or channel is adjusting.

File | Open recent
j) File | Open recent . . I don't expect to see script files in history here; only image files.

OT
PW seems pretty stable right now. Suggest
k) bump version to 8.01.xx and bump minor version with new functionality or major changes;
l) schedule releases once or twice a month unless critical error. If MS can release Windows once a month . . . Eight PW updates posted so far this month!?
Thanks!

[rfuerman]

(A) found the Color Curves transform | 'Autorange' menu item - its on the curve setting button. That's the setting button to the right of the curve.

m) color curves & auto range transforms have color space control *above* curve. Brightness transform has color space below curve. These should be consistent, no?

[jsachs]

b) Not sure what you mean here. The basic idea between this transformation has two parts -- first is identifying the black and white points in the input image which in turn makes use of thresholds to ignore outliers. Once the black and white points have been identified, by default they are mapped to pure black and white. If you want to map them to something else, you use the Dynamic Range slider and adjust the black and white markers to identify what brightness levels you want them to have.

c) If you turn off both auto black and auto white, the first part of the transformation does nothing, but you can still use the Dynamic Range slider to lighten the shadows or darken the highlights.

d) The reference in the help file is obsolete and I have removed it for the next release. The curve control in this transformation is used for display purposes and cannot be modified.

e) If you select RGB, you can autorange one channel as though it was a black and white image -- when I added this option I admittedly did not think it through very well. There is a crude color balancing technique that involves autoranging each RGB channel which is probably what I had in mind, but the current implementation would require running Autorange 3 times, so not very useful. As you say, this can already be done using Color Curves, so I may just remove RGB from Autorange.

[rfuerman]

b, c) I am confused. Auto range (black & white point) on auto range transform adjusts black & white point on X axis. Autorange on curve control settings menu does same. Help says "A dynamic range slider is a control used to specify a black and a white point for an image." But that is NOT what the dynamic range slider on Auto range transform does! The Auto Range | Dynamic range slider adjusts image *brightness* by moving the control points on Y axis. This does not appear correct to me - dynamic range slider should be consistent and adjust the X axis, no?
d) the curve control can be modified by dynamic range slider.
e, A) Obviously the Auto range feature for curves is very useful since PW devotes a transform to the option. Again suggest moving Curve transform autorange from the settings menu to a button or check box on curve dialog. This will make it easier to adjust R,G,Bs.
A) I struggle to find what functionality this Auto range transform has that the Levels & Color transform does not duplicate?? Auto adjust black & white points with Dynamic range slider; adjust threshold with Settings menu | threshold settings; and adjust brightness with midtones slider. Think I'll stick to L&C transform.

[jsachs]

b,c) I will take another look at the wording of the help file to see if I can make it less confusing.

Autorange works in two passes -- in the first pass, it identifies the black and white points based on the threshold sliders and the input image histogram. In the second pass it uses the Dynamic Range slider to assign where the black and white points are placed on the tone scale. This is necessarily different from the Dynamic Range slider in Levels and Color. The markers on the x-axis of the curve are set according to the black and white points that were identified automatically in the first pass. The markers on the y-axis reflect the dynamic range slider settings made by the user. The red curve is the actual brightness curve that is applied to the input image to create the output image.

You can do most or all of what Autorange does with Levels and Color, Brightness Curve or Color Curves, with the exception of controlling the autodetection thresholds. It is mostly there are a convenience (e.g. for use in batch processes) when all you want to do is stretch the image tonal range to run from full black to full white. Unlike the Autorange transformation, the autorange button in the Curve control is applied once and does not adjust itself automatically if the input image changes.

e) The curve control is already very crowded with buttons and auto range command duplicates a function that can be performed manually quite easily so I opted to place it in the Settings menu.