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<div dir="ltr">Could we set the value of the clamp? It could come in as defaults of 1.0 and 0.0, but we could alter it to whatever we wanted. At R&H, most of the time we clamped brights around 14-16. We'd only turn it down under that if we got bad pixels when rendering.<div><br></div><div>If you had a superbright red, like R 12, G 3, B 4, and you put a clamp of 1 on it, obviously it's going to set each value to 1, so what was red now reads as white. But it would still be useful.</div><div><br></div><div>After Effects clamp tool</div><div><a href="http://cdn.aescripts.com/media/catalog/product/cache/1/image/800x600/040ec09b1e35df139433887a97daa66f/f/t/ft-clamp-ui_1.png" target="_blank">http://cdn.aescripts.com/media/catalog/product/cache/1/image/800x600/040ec09b1e35df139433887a97daa66f/f/t/ft-clamp-ui_1.png</a></div><div><br></div><div>Nuke clamp is in the color grade node</div><div><a href="http://docs.thefoundry.co.uk/nuke/63/pythondevguide/_images/getMinMax_01.png" target="_blank">http://docs.thefoundry.co.uk/nuke/63/pythondevguide/_images/getMinMax_01.png</a></div><div><br></div><div>I'm not posting the images to say "this is how we should do it", but rather, to say it is useful and professional compositors would indeed use it often.</div><div><br></div><div>In fact, I was working on a shot this week that could have used it. I was given stock footage from a client, and I have no idea how much they'll color correct it in post once I deliver the final vfx shot. SO I have to make sure all my blacks are in line with what is in the plate. I put a gamma on the plate just to view the black levels and see how they match up when pushed really far.</div><div><a href="https://dl.dropboxusercontent.com/u/10553822/clamp_blacks_01.jpg" target="_blank">https://dl.dropboxusercontent.com/u/10553822/clamp_blacks_01.jpg</a></div><div><br></div><div>Since we don't have a clamp, I ended up putting a mix node right after the stock footage node, setting it to Lighten, and making the color over it black. then I slowly raised it while watching until the blacks all came in line. Would have been much easier to sample the value of the darkest dark I wanted in the shot, throw a clamp node on with the black clamp set to those values.</div><div><br></div><div>In fact, at R&H, the Black Clamp node let you set an individual value for R, G, and B. And it had a color picker so you could just sample the image and the values would fill in automatically.</div><div><br></div><div>Anyway, just throwing out my $0.02. Obviously I've found a workaround and can live with it, but it would sure be great to someday see a clamp node.<br><div><div><br><div><hr id="stopSpelling">Date: Fri, 23 May 2014 14:21:40 -0700<br>From: troy.sobotka@gmail.com<br>To: bf-compositor@blender.org<br>Subject: Re: [Bf-compositor] Clamping (Mix, Math, RGB Curves)<br><br><p dir="ltr"><br>
On May 23, 2014 1:56 PM, "Bartek Skorupa (priv)" <<a href="mailto:bartekskorupa@bartekskorupa.com">bartekskorupa@bartekskorupa.com</a>> wrote:</p>
<p dir="ltr">> When I say: "clamp blacks" I always mean: set every value below 0.0 to 0.0.<br>
> When I say: "clamp whites" I always mean: set every value above 1.0 to 1.0.<br>
> Every compositing artist will know what I mean.</p>
<p dir="ltr">If we can generate a clamp / scale node, I am all for it.</p>
<p dir="ltr">I am saying there is no concept of white in a scene referred model, and as such, you have to be careful as to not write nodes that break the system.</p>
<p dir="ltr">It is that simple. No white. No brighter than white. So sorry, “Every artist...” is actually “Every artist unfamiliar with HDR work.”</p>
<p dir="ltr">So a clamp node _must_ not make the erroneous assumption that 1.0 means anything special, and rather provide for an arbitrary value range.</p>
<p dir="ltr">If this all seems like speaking an alien language, it is precisely why I chimed in and said “Whoa.”</p>
<p dir="ltr">There are already nodes that are broken because of erroneous assumptions. It would be a shame to make more.</p>
<p dir="ltr">With respect,<br>
TJS<br>
</p>
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