All Things Color for Film and Digital Cinema
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Acquisition Formats

Coming Soon for Android – 2014 – Cinematography Color Grading Assistant application

Screen Grabs from my new Color Grading Application for Android.

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Color Grading Modes

  • Collaborate, Share and Manage OnSet “Looks” between DP, Colorist and OnSet DIT.
  • 3D Lut Support
  • Grading Modes – Levels – RGB Exposure ” Printer Lights” – 3 Way Color Correction
  • Database support for “look” tracking and management.
  • Includes effects for additional image treatment. (NB: THESE FUNCTIONS ARE NOT ASC CDL ‘AWARE’ )
    • Textures
    • Vignettes
    • Frames
  • All operations are “Live” and not compounded operations as in many other Android image processing apps.
  • or simply use as a professional Color Grading app for your Phone Stills (Lite Version) saving as PNG or JPEG.
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3 Way Color Correction

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Effect Modes – Vignette | Texture | Frames | Color Map

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All parameters are Live – No pre-rendering required between modes

Application includes:

  • 3d LUT support:
  • ASC SOP color Grading
  • Additional Image Effects
  • Android Screen Color Calibration
  • Export of ASC CDL grade files for Import into any color Grading Application.
  • Internal Database for managing grades:
    • Project Name
      • Shoot Day
        • Clip Name
  • Export Options:
    • “Extended Metadata” ASC CDL .cc file
    • Graded Reference Still
    • Original Ungraded Still
  • Preferences:
    • Help functions On / Off
    • User Name | Project Name | Shoot Day
    • Background Color
    • Load User Luts
    • Screen Calibration

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Adrian

 


iRiS S3D StereoScopic Base and Disparity Calc – new Skin Released

S3D Calc New Skin - template

New skin released with a few UI improvements.

Adrian


Video Waveform Visualization and Creation

As an addition to the prior post on waveforms here we examine a more visually descriptive way of showing how a video waveform is created and therefor how it can be interpreted.

Fig:1 Waveform and Live Image

Above we can see a standard Live Video Feed and its represented waveform.

Below I have created a 3Dimentional Luminance map of the same live feed. In this representation every pixel on the image is represented on the z-axis as a luminance value bw 0 and 1023 video code values. The ‘lighter’ or more intense the pixel value the higher it appears on the z-axis.

Fig: 2 Luminance Relief Map  Face On

As I rotate this image in 3D space, around the y-axis, you can see the luminance values more clearly represented as a Height map in the 3 Dimensional space.

Fig: 3 Luminance Relief Map Rotated 45 Degrees

When finally rotated a full 90 Degrees we end up with the Waveform interpretation.

Fig: 4 Luminance Relief Map Rotated 90 Degrees

Adrian Hauser


Waveform Vs Histogram interpretation in Digital Cinema Cameras

Understanding how to read Histograms present on many new digital cinema cameras can be tricky and are easily misenterpreted.

For analysis, I will use the below still from the film Daybreakers as reference.

Ethan Hawke in "Daybreakers" (2010)

The following snapshots have been taken using DpxRead available on the Panavision website.

Immediately we can see that there is a massive difference in the way these two images are represented in each of the graphical/statistical graphs.

Histograms represent the volume/percentage of light levels exposed within a particular image. The resulting graph shows the distribution/intensity plot of those levels.

Histogram Exposure

The above image reference image  is quite ‘moody’. The histogram shows us this quite literally but surprisingly shows nothing of where the midtones sit. This is because Histograms work with percentages and Ratios of light. If for the most part an image is dark, say 60% of the overall area , then the rest of the histogram has to be interpreted with the remaining 40 percent of image area. For that reason the intensity represented by the histogram for the remaining light values is visually a lot lower than the Dark spike shown in our reference.

To better show the way a histogram graphs an images lightness values I have put the below gradient into the scopes.

Linear Grayscale Ramp

We can see that because there is an even amount of each light level within the gradient image the Histogram shows an even intensity/distribution of each ‘level’.

Video Waveforms on the other hand give us a lot more visual information with which to evaluate your exposure and contrast ratio. As well as showing us the distribution of light values the graph is also plotted across the horizontal plane of the image. With this additional ‘axis’ one can easily determine where within the frame a particular item sits in its digital exposure value. This makes it easy to find for example the exposure of someones skin tone in relation to the background subject matter.

Histograms are Cheap and Easy to display from a programmers POV but in my opinion are quite useless in representing photographic content and should not be used for indepth exposure analysis.

Adrian


D-Lux. Website Live

dlux

See Website for more details.


DLux software update

Update and Progress – Dlux Onset monitoring software.

Recently I’ve been quitely buying and studying books on Cocoa programming and OpenGL programming to give the Dlux application more functionality.

Recently added:

- added ASC Color Correction and ASC saturation parameters

- Improved Output of XML and Imaging data to include ASC color SOP data together with 3DLut information.

- Improving handling of Raw Cannon and Nikon DSLR images (intended for film jobs where DOP can send stills of graded DSLR with grading info to rushes facility. 

- Improved handling of Live HDSDI video streams and Live Firewire HD Streams. 

- New release date scheduled for before IBC.

- Improved UI updating when recalling saved presets.

- integrating Full Screen Mode for single or double screen use with external monitor.

Ade

 

DLUX Updated GUI with ASC Color Correction


D-Lux

 

D-Lux  screen_capture

D-Lux screen_capture


Resize methods – shooting Red 3K for Post.

Over the weekend the were a few posts on the CML forums regarding shooting Red with non standard 3K files for post.  (Film standard being 2k or 4k).

My theory was that 3k is a non standard production/deliverable format and hence would at some stage have to be resized to fit standard deliverable Specs such as 2k or 4k film or HD for Video. In terms of downressing a 3k image digital filters must be applied to the pixels so an interpretation can be made of surrounding pixels to determine what pixel value is written. 

With this test I have taken a 2k reference image (I dont have any 3k reference files at hand) and performed a similar 1.5 scale reduction (emulating 3k to 2k) using different resize algorythms to see what the result would be like. I have chosen standard ‘out of the box’ filters available in most DI tools. Most of these filters inherently end up with artifacts that must be tested on the pictures at hand to see what filter best suits the production. The artifacts to look out for are Aliasing, blurring and Edge ‘Halo’ and jagged diagonals.

Unfortunately I dont have a Sinc filter at hand that is considered to be the best Downressing filter as it keeps small details without the ‘ringing’. I will add this to the data as I get a chance to go into work.

See Below. Click on each thumbnail to see the 100% cropped rendering of the transformation.

Here is a composite image of the comparison Data. 

Of particular note is the lack of all methods to efficiently interpret any of the ’40 lines’. In all cases this data, as ‘resolution’ is lost. You can also see interesting effects at each of the other resolution interpretations.  

 

3k to 2k resize comparison 

3k to 2k resize comparison

The basic conclusion looks like youd be better off shooting 2k but I will wait until I try the Sinc Filter. Upressing methods would probably give better results but then why not shoot 4k? 

Adrian Hauser


iRiS-LiveLut – Mac OSX – application update

An update on my OSX software ‘LiveLut’ which had some major coding breakthroughs over the last week.

Over the last few days I have successfully implemented the following features:

3DLut and color correction 25 fps ‘realtime’ previews to :

3dlut1

- Stills

movie

- Quicktime Movies

video

-and Live incoming Video. (excuse the dodgy iSight camera)

All on a Mac Book Pro.

It still needs a bit of love on the UI side of things although that should not take too long.

I also added a live data view showing the associations between Density, Code Values and Printer Lights from the ‘exposure’ based color changes.

And the ability to save reference stills. (some time in the future i’ll incorporate the ASC color data translation ;)

The initial release of the software will be a simple pared back version available for film-makers to reference when making Photochemical timing adjustments to Answer Prints. The second version will incorporate the Slope Offset and Power Color tools for reviewing Quicktimes with a 3Dlut applied. The third release of the software will enable on set previews of live images direct from the source. The out put can be tapped to an external DVI or HDMI enabled monitor. 

User 3DLuts can be made and loaded into the program.

Adrian


18 Percent Grey …. “Middle Grey” and Magic Numbers

 

    For a while I have been pondering the function of the 18 percent grey card. Why 18%, what is its historical reference…ect.

    After a lot of reference reading I came up with the following ….

    Traditionally 18 % refers to the statistical average reflectance of a photographed scene. ‘Normally’ exposed skin tones also generate an average incident light reading of about 18%.

    Photographically, if you were to make a set of 11 patches starting with 100% reflectivity and each subsequent patch was halved in reflectance, you would end up with a logarithmic scale where the light intensity is being halved each patch. The seventh step, middle grey, would yield a photographic Status M Neg density value of 0.7

    Using our Density math described in previous posts we know Transmission = 1/10^Density   

    Therefor    T=1/10^0.7= 0.18      AND       Transmission is directly proportionate to Luminance L*. Not boring you with the math the result is 49.496.

   So    0.7 Density = 0.18 Transmission = 50% Luminance(L*).

 

 

Fig.A - Status M against Status A Density

Fig.A - Status M against Status A Density

 

 

  Interestingly If we map our 21 step sensitometry readings of a 21 strip grey scale test wedge over Neg and Print densities we see that 0.7D is the cross over point !   See Fig.A

 

 

Fig.C

Fig.B

 

 

 

 

Looking at the image below, Fig.C, you will notice that this point of around 18 % grey is the mid point at which the cineon Log file is expanded when overlayed with a Print emulation 3DLookUp table. Both Mid Grey LAD Patch’s are almost identical as seen on the corresponding waveform Representations. 

 

 

18percent

Fig.C

 

Looking at the graph in Fig.C one can also see the reference point of 18 % on each of the mapped targets averaging around 50% luminance. Interestingly with this chart I have mapped Cineon Log levels against the 2.2 and 2.5 video gamma transfer functions and CIE Luminace L* values. They are all relatively close to each other in their Logarithmic encoding. I can see im going to have to rewrite this as its going to get messy from about here on in, although quite fascinating. 2.5 gamma looks like its the best match for CIE L* but somehow we got stuck with 2.2. Near enough is good enough I guess. It was decided back in the 8Bit video days that to help save on visual data that video/TV could also have a perceptual gamma encoding, once again mimicking the eyes response to nature. A gamma of 2.2 was decided apon.  

 

 

Adrian


Protected: On set monitoring Luts for Digital Film Acquisition

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Live-LUT

 

Live MBPro LUT monitoring application

Live MBPro LUT monitoring application

 

Live-LUT is a Mac Book Pro application for viewing live camera images via firewire on your Computer display. Live-LUT  allows users to apply 3d-LUT’s over the image and perform simple Lab-Style printer light Color corrections. 

Live-LUT can also be used to view LOG image sequences in the same context. Using the printer light controls Live-LUT can show you the result of lab printer light adjustments and their effect on the resulting release print.

Beta testing now.

Adrian


To monitor with a HD CRT on-set or not. Focus issues

zone_plateA number of digitally acquired feature films I have been recently working on had a number of surprising focus issues not before seen until projected full screen in its native resolution. Surprisingly the same images didnt look as soft and appeared a lot more acceptable on a HD CRT monitor in the same room.

As these display devices are not a true pixel for pixel representation of the captured image I would not recommend using them for critical focus judgement. Color yes but critical focus….. no. This is not the first time I have seen this.

Screen your rushes in native res each day if possible or also have a SDI tap to a HD flat screen Display. Perhaps winding up the sharpness on the CRT may work  as well. I’ll test this myself. 

Film images seem to be a lot more forgiving in this regard due to the apparent perceptual sharpness effect of the grain.

 Adrian


Acquisition Formats

1874 Jansen Revolver

1874 Jansen Revolver

This Category will grow over time with personal user information in relation to hands on experience with different acquisition formats and their flexability in the grading suite. To come soon will be Film, Panavision Genesis, Red, Sony HDcam, and prosumer formats.

View Posts Here.

Acquisition Formats

Adrian