Sony Gamma Curves User Guide

The selection of Sony CineAlta Gamma Curves curves provided by Light Illusion range from ones aimed to generate a pleasing image 'in-camera', through to curves that generate extremely low-contrast, high-dynamic range images.

The low-contrast curves are recommended primarily for when capturing to low compression, high bit-depth recorders (such as D5, HDcam SR, or to disc), with f900 cameras. With the 10bit 4:4:4 cameras there are no issues (although see note on f950 at the end of this page.) The reason for saying this is to minimise any issues with banding and other potential artefacts due to low bit depth and compression based recording.


Initial Operation

Gamma Curves

The curves are provided as a Zip files, and when extracted will show the necessary file structure format for the curves to be copied to a memory stick for camera use.

There are a maximum of 5 Gamma Curves allowed per memory card, and there are four card's worth of files for each camera or camera range.


Cineon profile Curves

These first curves are for use where the maximum DR range of the camera is required during capture, with all images requiring later post-production grading to generate a final deliverable images, just as with film capture to negative requires grading and printing.

The steeper the curve the more output change there will be for a given change of input. Hence the lower-contrast curves will generate stretched blacks, showing more shadow detail than the normal Rec709 based curves, combined with progressive highlights to prevent early detail clipping.

Compare the initial slope of these curves with the following MegaGamma curves, which are Rec709 based...

Light Illusion Gamma Curves - based on the Cineon/dpx format
Cineon Curve Details (NON-f900 Range)
  • DP-CIN-150c - 18%grey@50; 150%DR, Clip109%
  • DP-CIN-250c - 18%grey@50; 250%DR, Clip109%
  • DP-CIN-400c - 18%grey@50; 400%DR, Clip109%
  • DP-CIN-625c - 18%grey@50; 625%DR, Clip109%
  • DP-CIN-1000c - 18%grey@50; 1000%DR, Clip109%
    (requires +6db to prevent early clipping)
Cineon Curve Details (f900 Range)
  • DP-CIN-150c - 18%grey@50; 150%DR, Clip109%
  • DP-CIN-205c - 18%grey@50; 205%DR, Clip109%
  • DP-CIN-285c - 18%grey@50; 285%DR, Clip109%
  • DP-CIN-600c - 18%grey@50; 600%DR, Clip109%

MegaGamma profile Curves

The MegaGamma curves provide extended highlight detail, while retaining the Rec709 shadow and mid-tone.

Please note that curve 4 (green) is the maximum DR of the cameras in their default state. The fifth curve will require +3dB extended range to prevent early image clipping of the output.

Light Illusion Gamma Curves - aimed at generating a usable image in-camera
MegaGamma Curve Details (NON-f900 Range)
  • DP-MG-250c - 18%grey@45; 250%DR, Clip109%
  • DP-MG-350c - 18%grey@42; 350%DR, Clip109%
  • DP-MG-450c - 18%grey@39; 450%DR, Clip109%
  • DP-MG-650c - 18%grey@36; 650%DR, Clip109%
  • DP-MG-850c - 18%grey@33; 850%DR, Clip109%
MegaGamma Curve Details (f900 Range)
  • DP-MG-150c - 18%grey@45; 150%DR, Clip109%
  • DP-MG-205c - 18%grey@42; 205%DR, Clip109%
  • DP-MG-285c - 18%grey@39; 285%DR, Clip109%
  • DP-MG-410c - 18%grey@36; 410%DR, Clip109%
  • DP-MG-600c - 18%grey@33; 600%DR, Clip109%

Log profile Curves

These curves are a mid-way house between the above two extremes, using a Log profile to provide an image that is pleasing to the eye, while offering good shadow and highlight capabilities.

There are two versions of these curves, with only one different between the two sets of curves - on the first set has 18% Grey scaled with curve's DR value, while the second set has 18% Grey fixed at 42% of the output value.

Light Illusion Gamma Curves - 18% Grey scaled with DR value

Gamma Curves - 18% Grey scaled with DR value
LOG Curve Details (18% Grey Variable - NON-f900 Range)
  • DP-LOG-150v - 18%grey@50; 150%DR, Clip109%
  • DP-LOG-250v - 18%grey@45; 250%DR, Clip109%
  • DP-LOG-350v - 18%grey@42; 350%DR, Clip109%
  • DP-LOG-450v - 18%grey@40; 450%DR, Clip109%
  • DP-LOG-650v - 18%grey@38; 650%DR, Clip109%
LOG Curve Details (18% Grey Variable - f900 Range)
  • DP-LOG-150v - 18%grey@50; 150%DR, Clip109%
  • DP-LOG-250v - 18%grey@45; 250%DR, Clip109%
  • DP-LOG-350v - 18%grey@42; 350%DR, Clip109%
  • DP-LOG-450v - 18%grey@40; 450%DR, Clip109%
  • DP-LOG-600v - 18%grey@38; 600%DR, Clip109%
Light Illusion Gamma Curves - 18% Grey fixed at 42% output value

Gamma Curves - 18% Grey fixed at 42% output value
LOG Curve Details (18% Grey Fixed - NON-f900 Range)
  • DP_LOG_150f - 18%grey@42; 150%DR, Clip109%
  • DP_LOG_250f - 18%grey@42; 250%DR, Clip109%
  • DP_LOG_350f - 18%grey@42; 350%DR, Clip109%
  • DP_LOG_450f - 18%grey@42; 450%DR, Clip109%
  • DP_LOG_650f - 18%grey@42; 650%DR, Clip109%
LOG Curve Details (18% Grey Fixed - f900 Range)
  • DP_LOG_150f - 18%grey@42; 150%DR, Clip109%
  • DP_LOG_250f - 18%grey@42; 250%DR, Clip109%
  • DP_LOG_350f - 18%grey@42; 350%DR, Clip109%
  • DP_LOG_450f - 18%grey@42; 450%DR, Clip109%
  • DP_LOG_600f - 18%grey@42; 600%DR, Clip109%

Image Result

The following images show the variation and help understand the benefit of a low contrast, high dynamic range image.

Default video
'Default' camera video settings

709 shadow
Mid range Log curve

Log shadow
Full log curve

In the above images the difference is fairly obvious between the first image, which has no room for grading, with crushed shadows and clipped highlights, while the second two images show good shadow detail and highlights that are not clipped. These images can be graded to look exactly as required as all the detail throughout the whole dynamic range has been captured. The difference between the final two images is less, with the shadow detail and highlight being a little further extended in the second image.

Images curtesy of Geoff Boyle, CML, who is a great believer in the Light Illusion Gamma Curves.


Curve Loading

The following is the procedure for loading the Gamma Curves into a Sony CineAlta cameras. Once loaded the curves will disable some menu options, and it is best to set all other to off, or to their default. To check you have all the curves loaded connect the camera to a monitor and cycle through the curves; it will be obvious the curves are loaded by the various different looks you will see.

Please note that there is a bug with the Sony f950 CineAlta camera that will effect any Gamma Curves used with this camera - not just the Light Illusion curves. The problem is that in 4:4:4 mode the output image data levels get re-mapped to 4:2:2 levels when a CVP Gamma Curve is applied. This is not a serious problem as there is no clipping, just re-mapping of the output data. When loaded into a post system that expects 4:4:4 data to be valid from 0 to 1023 this will result in lifted blacks and lowered whites - which can easily be adjusted to be correct during any grading process.

f23/f35
  • Unzip the downloaded .zip file onto your PC.
  • Then un-zip the individual Gamma Curve zip files directly to separate Sony formatted memory stick
  • Load memory stick into camera slot
  • Load the gamma table data via a memory stick using the (USER GAMMA) page of the FILE menu in Custom mode
  • Position the menu pointer to READ (MS t CAM)
  • push on the MENU SEL/ENTER dial
  • Select USER on the first line of TABLE on the (GAMMA) page of the USER (PAINT) menu and display the desired user gamma
f900/f950
  • Unzip the downloaded .zip file onto your PC.
  • Then un-zip the individual Gamma Curve zip files directly to separate Sony formatted memory stick
  • Load memory stick into camera slot
  • Top Menu FILE - Go to page 4 (user Gamma) and LOAD memory stick.
  • Top Menu PAINT - Go to Page 3 (Gamma) - scroll down to Table - you see Standard and User options - select User - you will now see the files as a drop down option list - select curve and enjoy :o)
  • Select each curve once to see your favoured setting compared to the others.
f800
  • Unzip the downloaded .zip file onto your PC.
  • Then un-zip the individual Gamma Curve zip files directly to separate Sony formatted memory stick
  • Load memory stick into camera slot
  • Top Menu FILE - Go to page FILE and LOAD memory stick.
  • Top Menu PAINT - Go to page GAMMA - scroll down to Table - you see Standard and User options - select User - you will now see the files as a drop down option list.
  • Select each curve once to see it compared to the others.
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