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New Curve interpolation in Color Management works as the old method unless it gets reset.
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Description

System Information
Win7 64bit Nvidia 750Ti 4Gb

Blender Version
Broken: 2.76 578f70f

Short description of error
New Curve interpolation in Color Management needs to be reset to get it working with the new method.

Exact steps for others to reproduce the error
It's not file specific, it can be reproduced even on factory settings here, that's why i have no blends to attach.

Steps:

  • Load factory settings
  • Fresh new default file
  • Go to Color Management tab and tweak the curve by adding a point like the image attached
  • (Look how the curve behaviour is the old one)
  • Now Reset curve from the Tools
  • Tweak again the curve by adding a point
  • Now it is working as expected

Event Timeline

Marco G (marcog) added a project: BF Blender.
Marco G (marcog) set Type to Bug.
Marco G (marcog) added a subscriber: Marco G (marcog).
Marco G (marcog) created this task.
Marco G (marcog) raised the priority of this task from to Needs Triage by Developer.

That's because the points on each end of a new curve are now of the vector type by default (as opposed to the auto type they were before).

If you have an existing curve, change the point type for the ones at each end to 'vector'. You can do that by clicking the little blue wrench icon.

Sergey Sharybin (sergey) triaged this task as Needs Information from User priority.

@Marco G (marcog): I'm not sure what are the old and new methods? Can you explain that? And does this happen with facture Blender settings?

@Adam Friesen (ace_dragon), this i can not confirm. All the points are AUTO handle after the curve mapping is being enabled first time. So it's some operation which you do makes them VECTOR. Please give us exact steps you're doing to get point handle type from a factory startup.

@Sergey Sharybin (sergey) , yes, as stated, this happens with factory settings too.
I can't find the commit but i remember (probably you?) that the behaviour of the curve mapping has been modified (now it's better btw, IMHO), there is an example here in this thread, now a single point give a sort of automatic S shape ---> link BA

The bug i report is because to get this "new" way about how curve interpolates, it does not work out of the box, the user MUST reset the curve manually (even on a fresh new file on factory settings), otherwhise it works as the "old" way.

Please look the far left and far right shape of the curve in the image I attached. The far left is how it worked before, the far right is how works now (improved). Try following the steps i wrote.
The fact the user needs to reset manually the curve is IMHO, a bug, should work out of the box instead.

@Adam Friesen (ace_dragon) , the fact you need to reset or set to AUTO manually is *the bug* in my opinion.

@Sergey Sharybin (sergey) , i think D1658 is the patch i was looking for to explain the "old" vs the "new" method, so the far left in the image I attached is *before* the patch, far right is *after* the patch has been committed. But(!), to get this new result, you need to reset the curve, it's not working automatically as soon as the user adds a point to the curve.

Hope it's clearer.

Just to clarify, there was never changes in interpolation or so. There was only a change for the shutter curve in rB4f6b01ce1 which lead to all LINEAR curve preset to switch to a VECTOR handle. Official startup file has AUTO handles by default for the color mapping.

Now made it so Reset behaves same as in all previous releases for color management curve (and rest of single-slope curves actually). This conflicts with original report, but that's really how it used to work all the time and how it is expected to work.

Ah, ok thanks for clarifying.