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MarcoDebiasi

[AP] Improvements of Curves Function

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Hi,

 

I am another user interested in Affinity Photo as an alternative to Photoshop.

 

I have been familiarizing and playing with it after installing the beta version for Windows on my computer.

Overall it is OK. It is somewhat different from Photoshop and this will require me to go through some learning, all of which is fair and expected.

A part from bugs that need fixing, I think there is space for better implementation of some functions some of which are being reported in this forum.

 

I am adding one myself for the Curves function (under Tones in the Develop Persona).

Unless I am missing something, in its current implementation the curves function of Affinity allows to place and move points in the curve but does  not show the values of the input and output coordinates of the points. This makes very difficult (in fact, almost impossible) to exactly reproduce a similar curve profile on different photos. Photoshop not only shows the input and output values of each selected point of a curve, but also allows to directly enter such values in the corresponding fields without having to drag each point.

Also, similar to Photoshop, I think that showing a curve and its corresponding hystogram overlapped in the same graph helps to much better evaluate the effect of modifying a curve.

 

I hope this and other practical improvements will be implemented in Affinity to make its current and already quite impressive set of features even stronger.

 

Regards,

 

 

 

Marco Debiasi

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Curves is one of the most important tools in image editing app. It should be as smooth and flexible as possible. PS is very good and AP is quite good and responsive.

I wish there were auto white/black point buttons, with clip adjustment. Finding white/black points by hand adjustment is sometimes not so fast.

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Refer to the image below. Compared to other Curves implementations, I like these things:

  • the ability to work directly in HSV and HIS mode. Super handy. A simple saturation curve is quite powerful and simple to apply.
  • the option to open any curve in a scale-able window that can be resized to any size - as big as the screen, if needed. I just do not understand why most image editors will not allow the user to do this. Photoshop's curve palette is tiny, even in expanded mode! Curves are so important, and this is one of my pet peeves.  
  • thumbnails of curve presets.
  • the option to apply curve presets to specific channels.
  • various curve types: spline, langrange, bezier, line, text input, etc.
  • a preview option with a split view of which the split can be move to the left and right 
  • the option to quickly create a stepped curve.
  • the option to invert a curve.
  • the option to move the entire curve left, right, up, and down.

My main issue with Affinity Photo's curves is that it seems quite heavy on processing. On an older i5 Windows tablet (EPE121) the curves choke that machine, and adjusting the curves is almost impossible. I do not experience that issue with other image editors and curves adjustments are snappy and responsive.

 

Anyway, I feel it is a good idea to compare the various curves implementations, and learn from them.

 

I do like the alpha channel option in Photo.

 

dptgsi.jpg

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Hello,

 

I add to the curves improvement.

On PS, CO or LR you have different curves tools that shows a point or vertical line, over the curve or the histogram, while you are pointing your cursor over the image.

This way you can check different areas of your image and see the tone, to check if it's too light or too dark, or if it is into the 'correct' zone.

Lightroom have a tone curve tool where you can see the tone in % and before/after values; you can see a point on the curve without needing to edit the curve or place adjusting points.

In Capture One you can see a line on all the histogram tools (histogram, leves and curves) while you move over the image.

In PS, curves tool, while you press the left mouse button and move over the image, you can see the tone as a point that moves over the curve, before need to edit the curve.

But on AP, to see the tone of an area of the image, you need to click the picker button, then locate your area, drag a bit there, place a point on the curve, then after that you can see the tone of that area.

It would be really useful to see the tones of the image using the curves tools... or any other tool.

I use the LR tone curve tool to check tones on different areas of the image (light and shadows on faces, for example).

It happened me several times, when I end to edit a picture and send it for print, that the tones of the printing were a bit different compared to what I 'saw' on my monitor. The colors are ok, but I see darker tones near black and some light tones just pure wait on print. So now I check my pics with the tone curve tool before sending for printing, cheking if important areas are below 5% or above 90%, also if faces are into razonable values, so no matter if the bright of my monitor is not 100% correct, I check the real tones this way. This tool is really invaluable.

 

Regards.

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Hello,

 

I add to the curves improvement.

On PS, CO or LR you have different curves tools that shows a point or vertical line, over the curve or the histogram, while you are pointing your cursor over the image.

This way you can check different areas of your image and see the tone, to check if it's too light or too dark, or if it is into the 'correct' zone.

Lightroom have a tone curve tool where you can see the tone in % and before/after values; you can see a point on the curve without needing to edit the curve or place adjusting points.

In Capture One you can see a line on all the histogram tools (histogram, leves and curves) while you move over the image.

In PS, curves tool, while you press the left mouse button and move over the image, you can see the tone as a point that moves over the curve, before need to edit the curve.

But on AP, to see the tone of an area of the image, you need to click the picker button, then locate your area, drag a bit there, place a point on the curve, then after that you can see the tone of that area.

It would be really useful to see the tones of the image using the curves tools... or any other tool.

I use the LR tone curve tool to check tones on different areas of the image (light and shadows on faces, for example).

It happened me several times, when I end to edit a picture and send it for print, that the tones of the printing were a bit different compared to what I 'saw' on my monitor. The colors are ok, but I see darker tones near black and some light tones just pure wait on print. So now I check my pics with the tone curve tool before sending for printing, cheking if important areas are below 5% or above 90%, also if faces are into razonable values, so no matter if the bright of my monitor is not 100% correct, I check the real tones this way. This tool is really invaluable.

 

Regards.

yeah, so true 

 

@Herbert

sounds great, especially the resizing and the different interpolation modes! that is how curves should be!

somehow we should switch to Photoline I guess  :D  :lol:


 

 

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Agreed, numeric readouts are pretty much essential.

 

HSL/HSV curves are definitely an extremely useful feature (there even used to be a paid third party plugin for Photoshop I believe because Adobe just never got their act together).

 

However, a horizontal cubic bézier curve like in most video-focused applications (such as DaVinci Resolve) is much more easy to control for HSL/HSV adjustments compared to the Photoshop-type linearly ascending Catmull-Rom-Spline like that PhotoLine seems to used (judging based on the screenshots). In general, for some cases an option to use Bézier curves for other spaces like RGB would also be useful (in this case, the ascending version is fine).

 

One other point that bugs me about current Affinity Curves is that you can't select multiple points and move them together. And that the LAB curves default to the rather useless "Master" instead of, say, the "L" channel. And that switching channels is implemented as an annoying popup that requires an unnecessary additional click every time compared to, say, what Cocoa calls a "Segmented Control".

 

Alpha curves doesn't seem to work for me at all in recent versions, at least not on regular layers. I think it's a bug, but I might just be doing something wrong.

 

It would also be cool to have an option to highlight the zone that is targeted in the image view when moving the mouse over the curves. Similar to a clipping warning or QuickMask overlay, but for a zone of an adjustable number of tones around the one under the mouse. This way it would be immediately obvious which areas are being targeted. Sort of the reverse of what jmoren suggested about plotting the image pixel under the mouse cursor in the curves dialog. As soon as the user starts to drag on the curves, it would have to be hidden so that the adjustment can be judged properly, but then it would come on again after the mouse is released.

 

And of course the standard picker buttons for black point, white point, gray point. In addition, a white balance picker that adjusts the white point (gain) to make the color that was sampled neutral, but keeping the luminosity of the original sampled color the same instead of pushing it to white like Photoshop's white point picker does. Currently, if my image has a color cast that I want to fix by adjusting the gain (white point), I'd have to use a gray point picker and then manually adjust the white point until the curve is linear, which is an unnecessary waste of time.

 

And I'd love another picker mode with two color pots, so you can click one color and then a second, and it would place a curve point appropriately so that the source color will be mapped to the target color. Say you have an area of skin that has some unwanted light spilling on it and you want to match it to a darker, shaded area – just click one, click the second, and you have a perfect match. Or you can create a palette with target skin tones. load one color into the target pot, click the source pot, and you're 90% there.

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