LUT vs Gammut or Saver Gamma Issue

Hi,
So i have an Issue with the Saver Node.

32-Bit Loader EXR - VIEWPORT 1 ACTIVE
32-Bit Saver EXR - VIEWPORT 2 ACTIVE

"Gammut View LUT" :

Source Space : From image - Remove Curve
Output Space: Adobe RGB - Add Gamma

All looks fine with the lut in Viewport 1.

Saver:
OutPut Color Space: Adobe RGB
Output Gamma Space Adobe RGB ///////////////// < -- ---- Here is the problem.

Not the same blacks and brights as Viewport 1.

I dont get the same Pixelvalues in VIEWPORT 2 as the original in VIEWPORT 1.

It is like the iimage is getting Clamped or something. And i the EXR to EXR is just an exampel to isolate the issue. End goal is something like a TIFF. But still same behavior.

Saver and Loader have the exact same Bit depths set . Why is this? Same issue when RENDERED by the way.

Hope someone can help me out! Thank you

Not sure I follow your flow, it sounds like your double converting gamma.

Included is a simplified flow of how I work with linear EXRs. Convert color space before the saver with a "gamut" tool.

Code: Select all

{
   Tools = ordered() {
      Saver1 = Saver {
         Inputs = {
            ProcessWhenBlendIs00 = Input { Value = 0, },
            Clip = Input {
               Value = Clip {
                  Length = 0,
                  Saving = true,
                  TrimIn = 0,
                  ExtendFirst = 0,
                  ExtendLast = 0,
                  Loop = 1,
                  AspectMode = 0,
                  Depth = 0,
                  GlobalStart = -2000000000,
                  GlobalEnd = 0,
               },
            },
            OutputFormat = Input { Value = FuID { "TargaFormat", }, },
            ["Gamut.ColorType"] = Input { Value = FuID { "Space", }, },
            ["Gamut.GammaSpaceNest"] = Input { Value = 1, },
            ["Gamut.SLogVersion"] = Input { Value = FuID { "SLog2", }, },
            Input = Input {
               SourceOp = "Gamut1",
               Source = "Output",
            },
         },
         ViewInfo = OperatorInfo { Pos = { 1943, 167, }, },
      },
      Note1_1 = Note {
         Inputs = {
            Comments = Input { Value = "This converts the linear to chosen color space\r\n\r\n", },
         },
         ViewInfo = StickyNoteInfo {
            Pos = { 1559, 77, },
            Flags = {
               Expanded = true,
            },
            Size = { 196, 178.3, },
         },
      },
      Gamut1 = GamutConvert {
         CtrlWZoom = false,
         Inputs = {
            OutputSpace = Input { Value = FuID { "Adobe", }, },
            Input = Input {
               SourceOp = "Loader1",
               Source = "Output",
            },
         },
         ViewInfo = OperatorInfo { Pos = { 1589, 168, }, },
      },
      Note1 = Note {
         Inputs = {
            Comments = Input { Value = "All work done her is in linear space, use the viewer LUT to convert to chosen color space.\r\n", },
         },
         ViewInfo = StickyNoteInfo {
            Pos = { 622, 98, },
            Flags = {
               Expanded = true,
            },
            Size = { 196, 178.3, },
         },
      },
      Loader1 = Loader {
         Clips = {
         },
         Inputs = {
            ["Gamut.SLogVersion"] = Input { Value = FuID { "SLog2", }, },
            ["Clip1.OpenEXRFormat.RedName"] = Input { Value = FuID { "R", }, },
            ["Clip1.OpenEXRFormat.GreenName"] = Input { Value = FuID { "G", }, },
            ["Clip1.OpenEXRFormat.BlueName"] = Input { Value = FuID { "B", }, },
         },
         ViewInfo = OperatorInfo { Pos = { 184, 173, }, },
      },
   },
}

Hi ,
No Double converting of gamma, as i only use the LUT in the Viewport and working with Linear EXRs.

Same problem occurs if i add a "Gamut" tool. The LUT just doesnt correspond with the result i get after that operation.

If you have your "Pre-Gammut" node showing with Adobe RGB LUT in the left Viewport, do you get the same image in the right viewport , without the LUT and the same Adobe RGB profile when you are displaying your "Post-Gammut" node there?

I dont. The LUT and the Gammut Operation Differs.

/Regards

Strange, mine is working as expected, if you can copy and paste your flow, I'll try to take a look and see if I'm getting the same results you are.

Hi again,
I can create the same thing just by having a Loader connected to a Gammut downstream. Im starting to think it has something to do with the fact that im working on Still Frames?

You will have to be really zoomed in, or have a large number of brights and blacks to see the differens.

/C