curves in/ out min/max

[anon1]

what does it mean?

[R C-R]

That without any contextual clues whatsoever, you are inviting a lot of silly replies, some of them NSFO?  :lol:

[anon1]

did you use the curves dialog once?

then you know for sure that it is an obvious question 

[R C-R]

What curves dialog in what app & version?

[verysame]

I think it stretches or shrink the dynamic range, which say, for a 8bit image won't make magic.

 

 

• Input minimum—specify, in float, a minimum value to use as tonal input.
• Input maximum—specify, in float, a maximum value to use as tonal output.

 

From my understanding, it is similar to the output levels in PS, which I couldn't find in Affinity Photo levels:

 

[anon1]

I think it stretches or shrink the dynamic range, which say, for a 8bit image won't make magic.

well bit depth does not actually have anything to do with dynamic range but with precision

 

apart from that I appreciate your input and will think about it

 

cheers 

 

 

@ RCR you should probably check out curves https://forum.affinity.serif.com/index.php?/topic/18992-understanding-curves/?p=88071 it´s the most powerful tool as it´s the most versatile, although it did not get much love in the 1.5 update cycle 

[verysame]

well bit depth does not actually have anything to do with dynamic range but with precision

 

apart from that I appreciate your input and will think about it

 

cheers 

 

 

There's a relation, though: with higher bit depth you can technically store more information, hence a higher dynamic range.

[Fixx]

 

Well, I have no idea either what Input minimum and Input maximum mean here. First thought was that they define black and white points but that does not happen. Please enlighten me :-)

[anon1]

I think it stretches or shrink the dynamic range, which say, for a 8bit image won't make magic.

 

From my understanding, it is similar to the output levels in PS, which I couldn't find in Affinity Photo levels:

 

well that does not make much sense in curves because this is basically just moving the curve points vertically (if you just move curve points horizontally, curves are equal to levels)

 

 

But I think I sort of figured the I/O thing out

It says "Input minimum/ maximum" and what that means, I think, is the range of the input.

Your image has a certain spread of whites and blacks which is defined as a fixed range.

And the I/O values set to 0 and 1 which is the default set their end points to just these values, so they cover the range of your normal image. (range is equivalent to dynamic range in some sense here, although that range is the same for every image in a given color space)

 

When you enlarge the difference between the I/O values to -100 I and 100 O then you spread the input range of the curves more, the range that is covered by your image stays the same though. 

You can see the effect by drawing a gradient and then modifying the curves.

You´ll se a much more drastic effect.

This is because a smaller movement now has greater effect because the range that your image covers, in comparison to the range the curves input range covers is very small so it is much like "zooming out" of the curves window. Your actual image now only covers a very small part of the curves dialog input range.

 

this part if still a bit half-baked:

If you modify only the I or only the O value (or both to a different extend) you will shift the balance between effecting the highlights versus the shadows.

If you keep the I at 0 but set the O to 10 your image covers less percentage of the right side/ of the whites and thus a smaller modification in this area will show greater effects than before.

 

If you lower your input minimum to say -5 then your blackest black of your image is mapped against a bigger value and thus becomes less black/ more grey

 

 

if you set I to the same value as O then you don´t map anything and your curves have no effect at all 

 

hope this is remotely correct and helps!

 

cheers 

[kirkt]

To experiment with this feature of the Curves adjustment, try the following:

 

Make a new document - 32bit. This gives you an unbounded (not constrained between 0 and 1) working document. Now, use the rectangle tool, or whatever, and make a box and then use the color chooser to make boxes with various exposures. I have made one for you - you can download the .aphoto file here:

 

https://www.dropbox.com/s/8l13orpca6xr8x1/Unbounded.afphoto?dl=0

 

The example file has a large rectangle that is 0EV and four rectangles below 0EV (-1, -2, -4, -8) and four above 0EV (+1, +2, +4, +8). In 32bit color, you can express these values in "intensity" (like log photographic exposure or stops) or in floating point (FP) values. Normally, a bounded working document has all values between 0 (black) and 1 (white). An unbounded document can have any intensity values - presumably even negative ones.

 

The 32bit document is linear, so doubling the FP value doubles the intensity, equivalent to increasing by 1 photographic stop, or EV. The Color Chooser in AP takes on a special form in a 32bit document, permitting you to choose "color" (RGB values) and intensity (in Stops). You can also dial in both using the FP values. The relationship between EV and FP values is:

 

FP Value = 2^(EV).

 

To visualize values beyond the display range, you can use the 32bit preview tool (Studio > 32bit preview). Slide the Exposure slider to adjust the range of values displayed in your 32 bit document. You will see that the current document shows you the rectangles that are in the range between 0 and 1. Dial in negative exposure and you will see the upper +EV rectangles appear.

 

In the document I provided, there is a curves adjustment layer at the top of the layer stack. You can use the min/max input values to specify what range of FP values you want to comprise the lower and upper bounds of your curves adjustment. Try setting the max input to 0.25 and pulling the white point node down to the horizontal axis (0 output). Notice that only the squares that have a FP value <=0.25 are affected. Etc.

 

This way you have a true 32bit curves adjustment that you can control the range of input values that get affected in 32bit mode.

 

Totally cool!

 

[anon1]

This way you have a true 32bit curves adjustment that you can control the range of input values that get affected in 32bit mode.

 

Hm OK very cool, thank you so much for the detailed explanation! Much appreciated!

 

I somehow can´t find this fancy color chooser though 

[kirkt]

To bring up the 32 bit color chooser, double click on the circlular color patch in the chooser to bring up the dialog in the image I posted above.

 

Kirk

[anon1]

To bring up the 32 bit color chooser, double click on the circlular color patch in the chooser to bring up the dialog in the image I posted above.

 

Kirk

wow nice

seems like it lacks some documentation though 

 

thanks again!

[kirkt]

It is the place to read FP color values too. I'd like the FP values to be displayed under the cursor or with color targets in the info panel.

 

Kirk