P: Gradient editor needs a few improvements

[FeedbackCommunityMember]

It is almost impossible to use the gradient editor to simulate blending between lights, because it draws a straight line through RGB space. It would be good to be able to select HSL and LAB colour spaces for the gradient editor, and it would be even better if you could make bezier curves through RGB space, like the free tool at http://www.foddy.net/2010/10/gentle-g... is pretty frustrating that there was more flexibility in Deluxe Paint IV's gradient tool 23 years ago than there is in Photoshop's gradient tool now.

[bennettf96052341]

Forget it Herbert, it's never going to happen. And to be fair, the current code was written 15 years ago so there's probably nobody at Adobe who remembers how it works.

[FeedbackCommunityMember]

I have given up on Photoshop. I am using Acorn, which doesn't provide as many customization options, but usually delivers exactly what I want without effort. The two types of gradients it provides, regular and smooth:

[bennettf96052341]

BTW I did a quick test with the latest (2015) versions of illustrator and photoshop to double check. I think the reason Illustrator's one seems less bad is that it's doing simple linear interpolation, which is cruder but more predictable - but you'll see that both of them are pretty bad when it comes to smoothness.



Honestly I could live with it if Photoshop just did the illustrator thing, with a simple linear line in RGB space. My issue is that Photoshop's 'cubic' interpolation just clearly doesn't work as specified. Cubic splines do not have sharp corners in them, sorry!

[FeedbackCommunityMember]

Change Photoshop's smoothness to zero and you get a linear interpolation.

Yes, cubic splines that interpolate (not approximate) can have corners where they intersect the control points. Your "smooth" gradient doesn't even have the same magenta color you selected in Photoshop or Illustrator.

[bennettf96052341]

Like I said, it was a quick test. If you really need further convincing I can make you a version where the color stops are exactly identical, but the point here is that there should not be a discontinuity in the Photoshop gradient no matter what the colors are.

And yes, I *do* have it set to 100% smoothness.

[FeedbackCommunityMember]

Again, an interpolating cubic spline can have some corners when it hits the control points.
It looks like your "smooth" test isn't hitting the control points and just approximating them instead (which gets a smoother curve, but not the colors you specified).

[bennettf96052341]

Yes, it is technically true that a piecewise cubic spline interpolation with discontinuous derivatives can have corners. Is there some reason why you prefer to use an interpolation with discontinuous derivatives? The only reason I can think of is that you're trying to avoid the curve overshooting the edges of the RGB cube and 'clipping'. But the price is that your gradients are not remotely smooth even when the RGB line goes nowhere near the boundaries.

[FeedbackCommunityMember]

We use a very standard interpolating cubic spline. We need to interpolate the color stops, not just approximate them.

[bennettf96052341]

No I get that you need to hit the color stops, that makes complete sense. But It would be easy enough to construct a spline that hits all the stops and has a continuous derivative, right?

[FeedbackCommunityMember]

It already has a continuous derivative (assuming you set it to 100% smoothness), it just isn't as smooth as an approximating spline.

[bennettf96052341]

For example, here's an simple interpolation that DOES hit the exact same color stops, but has a continuous derivative

[Herbert2001]

In Photoline both linear and cubic interpolation are available for gradient stops. And both look great.

Krita and Gimp offer 5(!) different gradient interpolation methods - and for each gradient segment the interpolation method is independently controllable: linear, curved, sine, sphere increase, and sphere decrease.

I fail to understand why Photoshop's gradients are of such low quality in this day and age, and the only way to control the interpolation is to keep adding more and more stops. There is no need. Mr. Cox mentioned the code behind the gradient interpolation stems from version 5?

Well, about time for an update then. I submit that this thread has conclusively identified an issue with gradient quality in Photoshop, and it is time for Mr. Cox to admit that this ought to be addressed and improved.

[Herbert2001]

I agree. There have been a number of other legacy issues which are perceived as features by Mr. Cox. At this point I feel they will never be addressed.

[bennettf96052341]

Here's the full notebook in case anyone wants to reproduce or tweak

[Herbert2001]

What did you use to visualize the math?

[bennettf96052341]

Mathematica

[davep61284792]

Bennett. You are beating a dead horse. I saw your tool, it is really nice and way more comprehensive and accurate compared to Photoshop. Chris knows everything and he thinks Photoshop is a perfect tool with no room for improvements.

[rene_schmidt_6ouboq4vp4n2f]

bwahaha the Sr. Scientist snark strikes again.

[FeedbackCommunityMember]

Probably because the gradient editor sucks.

[FeedbackCommunityMember]

Why can't it function like Gradient tool in Illustrator? That one is much more user friendly and doesn't need so many steps to get to the same results.

[rene_schmidt_6ouboq4vp4n2f]

Answer: they don’t care.

They got your money and raked in huge profits with the subscription model, with loads of buggy new “features”, but no resolves for long-standing issues. What incentive do they have to fix this? Pfffft.

I mean really, look how long this thread is and how old it is.

[FeedbackCommunityMember]

What a moron chris cox is

[baer1]

UPDATE! In today's new release of Photoshop we have enabled multiple gradient interpolation options:

Perceptual, the new default method: smoothness controls interpolated using OKlab color space
Linear: interpolates using linear color space

Classic: interpolates using the selected working space. 

Learn more here: https://helpx.adobe.com/photoshop/using/gradient-interpolation.html 

Special thanks to @bennettf96052341 for his gracious feedback 🙂