jackpfeiffer
June 3rd, 2004, 04:25 AM
LUTs EXPLAINED: background and free Tuts....
Hi All..
A lot of people have asked me about LUTs -
- What are they?
- What are they used for?
- How do they Work?
Here is some helpful background info for you to better understand what a LUT is and how it is used...
"Look Up Tables" (LUTs) explained: Computer monitors can only display 8 bits per channel. This setting results from the monitor's display adapter and settings. Usually, you would set the display adapter to "True Color", or a 16, 777, 216 color palette. This number equals a bit depth of 8 for the three color channels. When you want to use the monitor to display a higher bit depth for such files as Cineon and DPX, you use a view LUT to display the higher bit depth in the 8-bit color space by mapping the colors. The image data is not affected by the conversion. Using the view LUT is also useful for leaving footage in logarithmic color space from input to output (import to rendering) while displaying the data in a linear way in the viewport. Specifically, this lets you work with Cineon and DPX files without converting from logarithmic color space. You can use a view LUT to also calibrate a monitor. To help you with this, the View LUT panel includes a feature for
displaying test patterns. Simply put, Output Look Up Tables help maps the 8 bit intensity information onto 24 bit false colour space.
Here is a more complete definition, compete with images: http://www.sli.unimelb.edu.au/envis/automap/colordepth.html
Therefore, more simply put, the concept of LUTs applies to the problems faced by the conversion of 10 bit Log Film to 8 bit Linear or Video Data... Video simply does NOT have the color depth necessary. Therefore, an intermdiate file, quite often a Cineon file, is created. Next, a LUT is used by video-based programs such as Combustion to best view the results and achieve a resemblance of color accurate viewing...
What are Cineon Files? Definition of Cineon Image File Format: The Cineon image file format is a subset of the ANSI/SMPTE DPX file format.
Read More Here: http://www.cineon.com/file_format.php
There is an On-Line Technical definition of the Cineon file format here: http://www.cineon.com/ff_draft.php
How do you convert 10 bit log images to 8 bit linear images? Answer: Read the lengthy article here: http://www.cineon.com/conv_10to8bit.html
As for Combustion: Basically, combustion has "Film Tools" -- specifically grain, color management and LUTS. The Grain and Color Tools are compatible with Discreet's other effects systems including flame and inferno. The combustion "add grain" tools include settings for most common Kodak film stocks, as well as full parameter control for automatically matching to any film type used in production. combustion can basically remove grain by using some pretty sophisticated math (algorithms) that reduce grain in an image, all without sacrificing image clarity. Combustion Look Up Tables, which are a set of controls that describes specific pixel values to be used in image display or conversion. These tools provide controls on a per-footage level (histogram, separate RGB controls), as well as tools to preview results of LUT operations on the monitor without having to use external utilities. The LUT files are compatible with flame and inferno and support similar editing, import and export functions to generic ASCII LUT files.
Wanna know even MORE about LUTs ?? Here's some more websites with additional info:
http://www.dai.ed.ac.uk/HIPR2/colmap.htm http://www.sgi.com/software/opengl/advanced97/notes/node131.html
http://www.cee.hw.ac.uk/hipr/html/colmap.html http://www.etl.go.jp/~matsui/eus/manual/node141.html
And finally, here are three free tutorials on LUTs:
1) At the CreativeCow.net website, Alan Edward Bell demonstrates how to work with Cineon files and combustion. Follow along here:
http://www.creativecow.net/articles/bell_alan/bit_depth/index.html
2) A tutorial on "Establishing Unity LUTs for Film Work," posted at FXGuide.com, written by: Peter Webb
see: http://www.fxguide.com/fxtips-236.html
3) "Color Grading using a LUT: Professional Film Graded LUTs in combustion, flame, fire or other applications"
at FXGuide.com, by: Peter Webb see: http://www.fxguide.com/fxtips-235.html
Have fun, and keep combustin' !
regards,
jack
denmark
Hi All..
A lot of people have asked me about LUTs -
- What are they?
- What are they used for?
- How do they Work?
Here is some helpful background info for you to better understand what a LUT is and how it is used...
"Look Up Tables" (LUTs) explained: Computer monitors can only display 8 bits per channel. This setting results from the monitor's display adapter and settings. Usually, you would set the display adapter to "True Color", or a 16, 777, 216 color palette. This number equals a bit depth of 8 for the three color channels. When you want to use the monitor to display a higher bit depth for such files as Cineon and DPX, you use a view LUT to display the higher bit depth in the 8-bit color space by mapping the colors. The image data is not affected by the conversion. Using the view LUT is also useful for leaving footage in logarithmic color space from input to output (import to rendering) while displaying the data in a linear way in the viewport. Specifically, this lets you work with Cineon and DPX files without converting from logarithmic color space. You can use a view LUT to also calibrate a monitor. To help you with this, the View LUT panel includes a feature for
displaying test patterns. Simply put, Output Look Up Tables help maps the 8 bit intensity information onto 24 bit false colour space.
Here is a more complete definition, compete with images: http://www.sli.unimelb.edu.au/envis/automap/colordepth.html
Therefore, more simply put, the concept of LUTs applies to the problems faced by the conversion of 10 bit Log Film to 8 bit Linear or Video Data... Video simply does NOT have the color depth necessary. Therefore, an intermdiate file, quite often a Cineon file, is created. Next, a LUT is used by video-based programs such as Combustion to best view the results and achieve a resemblance of color accurate viewing...
What are Cineon Files? Definition of Cineon Image File Format: The Cineon image file format is a subset of the ANSI/SMPTE DPX file format.
Read More Here: http://www.cineon.com/file_format.php
There is an On-Line Technical definition of the Cineon file format here: http://www.cineon.com/ff_draft.php
How do you convert 10 bit log images to 8 bit linear images? Answer: Read the lengthy article here: http://www.cineon.com/conv_10to8bit.html
As for Combustion: Basically, combustion has "Film Tools" -- specifically grain, color management and LUTS. The Grain and Color Tools are compatible with Discreet's other effects systems including flame and inferno. The combustion "add grain" tools include settings for most common Kodak film stocks, as well as full parameter control for automatically matching to any film type used in production. combustion can basically remove grain by using some pretty sophisticated math (algorithms) that reduce grain in an image, all without sacrificing image clarity. Combustion Look Up Tables, which are a set of controls that describes specific pixel values to be used in image display or conversion. These tools provide controls on a per-footage level (histogram, separate RGB controls), as well as tools to preview results of LUT operations on the monitor without having to use external utilities. The LUT files are compatible with flame and inferno and support similar editing, import and export functions to generic ASCII LUT files.
Wanna know even MORE about LUTs ?? Here's some more websites with additional info:
http://www.dai.ed.ac.uk/HIPR2/colmap.htm http://www.sgi.com/software/opengl/advanced97/notes/node131.html
http://www.cee.hw.ac.uk/hipr/html/colmap.html http://www.etl.go.jp/~matsui/eus/manual/node141.html
And finally, here are three free tutorials on LUTs:
1) At the CreativeCow.net website, Alan Edward Bell demonstrates how to work with Cineon files and combustion. Follow along here:
http://www.creativecow.net/articles/bell_alan/bit_depth/index.html
2) A tutorial on "Establishing Unity LUTs for Film Work," posted at FXGuide.com, written by: Peter Webb
see: http://www.fxguide.com/fxtips-236.html
3) "Color Grading using a LUT: Professional Film Graded LUTs in combustion, flame, fire or other applications"
at FXGuide.com, by: Peter Webb see: http://www.fxguide.com/fxtips-235.html
Have fun, and keep combustin' !
regards,
jack
denmark