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Color management

Bview offers the possibility to manage your media color by using simple features :

  • Apply a color space
  • Apply a LUT
  • Manage the gamma and brightness

../rsrc/img/Color_Management.jpg

In addition to this, two other advanced features are available : LUT and CDL.

LUTs

In image processing, a lookup table (also known as LUT) is used to transform the input data into a more desirable output format.

How to use

At the moment, only .3dl (Autodesk) file can be used for LUTs.

It can be loaded at Bview start using the command :

bview -luts file_name


You can also use a config file (regular text file) which contains a list of LUTs to load them altogether.
The config file must contain one or several lines with the following syntax : lut_label=path/file_name.3dl(INPUT_COLOR_SPACE;OUTPUT_COLOR_SPACE)

Example :

LUT1=/work/LUT/lut1.3dl(CINEON;SRGB)

#lut_label = LUT1
#path = /work/LUT/
#file_name = lut1.3dl
#INPUT_COLOR_SPACE = CINEON
#OUTPUT_COLOR_SPACE = SRGB

You can add comments by starting a line with #.
INPUT_COLORSPACE / OUTPUT_COLORSPACE supported values : LINEAR, CINEON, SRGB, REC709, PANALOG, REDLOG and LOGC.


If you have a LUTs library it is also possible to load multiple files at the same time. For instance you simply need to set up a file containing the needed LUTs.

Example : file is named all_luts.txt

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LUT1=/work/LUT/lut1.3dl(CINEON;SRGB)
LUT2=/work/LUT/lut2.3dl(LINEAR;REC709)
LUT3=/work/LUT/lut3.3dl(PANALOG;LOGC)

Now, load the file :

bview -luts all_luts.txt

In Bview, press F12 to open options panel then go to tab LUTs. All specified LUTs are displayed.

../rsrc/img/Color_LUT.jpg

How to use with Bview interface

LUTs are also manageable directly in the options panel (F12).

  • LOAD : add a lut to your project (specify path, label, input and ouput color space).
  • EDIT : edit an existing lut.
  • DELETE : delete an existing lut.

You can apply a global LUT (from top toolbar) or use Display LUT from the media panel to set up a specific LUT for your module. The Display LUT always overrides a global LUT.

../rsrc/img/Color_DisplayLUT.jpg

LUTs are saved in the project (.bv). They are not permanently stored in Bview.

ASC CDLs

The American Society of Cinematographers Color Decision List (ASC CDL) is a format for the exchange of basic primary color grading information between equipment and software from different manufacturers. The format defines the math for three functions: Slope, Offset and Power. Each function uses a number for the red, green, and blue color channels for a total of nine numbers comprising a single color decision. A tenth number, Saturation, specified in the Version 1.2 release, applies to the R, G, and B color channels in combination.

How to use

A CDL is an .xml usually saved under .cc, .ccc or .cdl.

You can create your own CDL file and then load it into Bview.


Exampe of .ccc :

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<ColorCorrectionCollection>
      <ColorCorrection id="CDL_A">
              <SOPNode>
                   <Slope>2 1 1</Slope>
                   <Offset>0 0 0</Offset>
                   <Power>1 1 1</Power>
              </SOPNode>
              <SATNode>
                   <Saturation>1</Saturation>
              </SATNode>
        </ColorCorrection>
        <ColorCorrection id="CDL_B">
                <SOPNode>
                     <Slope>0.9 0.7 0.9</Slope>
                     <Offset>0 0 0</Offset>
                     <Power>1 1 1</Power>
                </SOPNode>
                <SATNode>
                     <Saturation>1</Saturation>
                </SATNode>
       </ColorCorrection>
</ColorCorrectionCollection>

As for LUTs, CDLs are also managed from the options panel (F12). A text file listing multiple CDLs can also be use the same way.
You can either create them from scratch by setting a path and file name with the parameters or load existing files.

../rsrc/img/Color_CDL_New.jpg

../rsrc/img/Color_CDL_Load.jpg

Contrary to LUTs, CDLs can be applied on a module and a sequence or movie :

../rsrc/img/Color_DisplayCDL.jpg

CDLs are saved in the project (.bv). They are not permanently stored in Bview.
When a sequence or movie has no CDL applied but the module has, color correction from module is applied.

BUF Compagnie - Documentation. 2015-04-04.