See here for end user endorsements for the Light Illusion Gamma Curves for Canon's EOS cameras.

Alfonso Parra, AEC, has written a second document looking in-depth at the new Light Illusion LOG Gamma Curve for the canon EOS cameras.

Canon Cameras
Compatible Canon cameras are any that are EOS Picture Style compatible, including:

• 1D Mark IV
• 5D Mark II
• 7D
• T2i
• etc...

These curves are 3rd Generation, building on the success of the earlier variants.

Pre-Built Gamma Curves
The selection of curves provided by Light Illusion attempt to maximise the capture capabilities of the Canon EOS cameras, enabling the most to be made of the images in later post-production, and are based on the very successful Sony Gamma Curves, also from Light Illusion.

While there are limits as to the amount of improvement that can be made with these cameras, using in-camera Gamma Curves helps a lot as they are applied to the image as it is read from the image sensor, pre-compression, and so the advantages are obvious.

Canon Default Settings (no Gamma Curve or LUT applied)

Gamma Curve - Light_Illusion_CW-01

Gamma Curve - Light_Illusion_CW-02

Gamma Curve - Light_Illusion_CW-03

Gamma Curve - Light_Illusion_LOG-01

As always, test and evaluate the curves prior to using them for real jobs. It is possible that the stretched nature of the high-dynamic range, low contrast curves may push the image data beyond the spatial resolution available with the 8bit capture system and compression employed by the cameras.

CW - Centre Weighted curves
The 'CW' curves are Centre Weighted curves, that aim to minimise the problems associated with the camera's compressed format. These are the better curves to use, and under 90% of shooting conditions curves 1 and 2 will be ideal.

LOG - Cineon profile curves
However, due to popular demand, the last curve is a LOG based curve based on the standard Cineon LOG image profile. But, very importantly, the profile is NOT an exact clone of the Cineon LOG profile as this would compress the Dynamic Range of the captured scene into a smaller range of image data than is available with the 8bit signal, further compromising the image quality. This is the case with alternative LOG based curves that are available from other suppliers.

As a result of the gamma curve not being a true clone of the Cineon LOG profile a set of LUT data is also provided for the curve, enabling the user to post-adjust the image into true Cineon LOG format if required, as well as a selection of viewing LUTs to show the image in 'film print' and 'video' form.

These LUTs are not suggest for grading use as they will further compromise the image, but can be used as a viewing check.

For maximum quality it is always recommended to grade the original image directly, through a DI calibration LUT if being used for the project.

The following images show the Cineon LOG curve possibilities when combined with the provided LUT data.

LUT Applied to LOG image - LUT_Light_Illusion_LOG-01_to_CIN (makes a true Cineon LOG profile)

As can be seen from the above image, applying the LOG-to-Cineon LUT generates an image that fully matches the Cineon LOG format, compressing the full image Dynamic Range into a smaller range.

The combination of the original LOG-01 Gamma Curves with the LOG-to-Cineon LUT generates a compound Gamma Curve result that is true Cineon LOG:

As mentioned previosuly, and as can be seen in the image above, the problem is the compression of the scene range into a smaller bit depth range, causing problems with the 8bit compressed image format. This is the approach that has been taken by some of the alternative LOG or film style curves out there. Comparing this curve to the Light Illusion LOG-01 curve shows the difference in the data range used.

At lease with the LOG-01 curve the supplied LUT data to map to true Cineon LOG can be applied in post, after the 8bit H264 data has been translated to 10bit or more. This does minimise the problems, but this is still not a workflow Light Illusion suggests is applied.

To this 'Cineon LOG' image a Cineon LOG to Print or LOG to Video LUT can be applied for viewing., depending on the final delivery needs.

LUT Applied - LUT_Light_Illusion_LOG-01_CIN_to_PRINT

LUT Applied - LUT_Light_Illusion_LOG-01_CIN_to_VID

For viewing, the LOG to Cineon step is not required (it's provided for completeness really), and the original LOG image can be viewed directly through the following LUTs to emulate the whole chain.

Gamma Curve - Light_Illusion_LOG-01 (original LOG image)

LUT Applied - LUT_Light_Illusion_LOG-01_to_PRINT

LUT Applied - LUT_Light_Illusion_LOG-01_to_VID

Note thet the last two LOG-01 based images with view LUTs applied match the full Cineon LOG image with their View LUTs applied.

The curves are provided as a Zip files, and when extracted will need to loaded into the camera via Canon's EOS utility as Picture Files. See Canon Picture Styles for loading information, and if you are out on location and don't have the EOS utility installed, or have the CD with you, see Install Canon camera software without CD.

For additional information on these curves please contact steve@lightillusion.com.