Test chart

The idea of the following testchart is to follow artefacts through HD post-production. The artefacts include color transcoding errors, framing errors, subsampling and compression artefacts.

The computergenerated file is encoded in 8bit RGB space and available as a TIFF file. The file can be imported to a HD-NLE system and inserted into HDCAM tape before processing (these encoding processes will already alter the content).

The chart can then be examined by eye, on the waveform monitor and be exported back to an RGB file to be compared in an image processing program.

Please send comments on this file to matti@belle-nuit.com.

Download

The testchart is available in multiple resolutions:

1920 * 1080 testchart.tif (396 KB)
1280 * 720 testchart720.tif (216 KB)
720 * 576 (PAL) testchartpal.tif (152 KB)
720 * 486 (NTSC) testchartntsc.tif (126 KB)
720 * 480 (NTSC DV) testchartntscdv.tif (126 KB)

We recommend to use the appropriate file for each format.
The compression on the file is lossless (LZW).
To download, control-click on the link and select the context menu "Download Linked File".




Features

Cropping

The green triangles at the edges show full frame limits, so you can easily detect overscan on the monitor, and cropping on downconversion or on file conversion.

The horizontal green lines show cropping to film out 1.85, if you apply it symmetrically.

The vertical green lines show cropping to film out 1.66, if you apply it symmetrically.

The green rectangle shows safe title area (10% on each side).
Note for standard resolution files: The 1.85 and 1.66 lines are shown only respective to 4:3 aspect ratio. Lines respective to 16:9 are in preparation.

Color bars

Full size color bars are 75%: white is at 235, black at 16, colors at 180 each.

100% color bars are provided on the bottom right: white is at 235, black at 16, colors at 235 each.
100% color bars downconverted to composite PAL or NTSC would exceed limits.

Super white and super black

The super white regions show super white (255), whites near super white and white (235).
File conversion should preserve super white area, but some algorithms may remap 16-235 to 0-255. You should be able to measure a difference between 255 and 251 on the waveform. On an aligned video-monitor, you should see a difference between 231 and 235, but regions above 235 may appear uniform if clipping occurs.

The super black regions show super black (0) and the blacks near super black and black (16).
Black below 16 is not a useable area. Some conversions clip below 16, some remap and some preserve. On an aligned video-monitor, you should see a difference between 16 and 20, but 16 should look the same with numbers below (4,8,12).

Gray scale

On the bottom left, a gray scale is provided with 8 steps from 0% to 100%. The numeric values (rounded) are: 16, 43, 71, 98, 126, 153, 181, 208, 235.
The gray scale will show you gamma corrections applied to the image. With a gamma correction over 1.0, gray value will be higher than nominal, with a peak in the difference on the 126-tab. If the peak is on the 71-tab, then probably a black stretch has been applied.

Horizontal and vertical resolution

The black and white lines show horizontal and vertical resolution in number by scan lines. A second area is displaced by one line at the same resolution to detect eventual phase artefacts.
You may detect compression and resampling and generation-loss artefacts.
Horizontal loss in resolution is normal with HDCAM-codec, but there should not be loss in vertical resolution.

The red and cyan lines will show color subsampling.
A standard HD-SDI signal at 4:2:2 subsampling will show reduced horizontal resolution.

Ramps

The black and white ramp can detect histogram defects (posterization) due to color correction. The ramp is slightly off horizontal to better detect the effect visually.
This ramp is only 8bit resolution.

The blue ramp also detects errors due to color space conversion in 8bit resolution.

Color space encoding tabs

The encoding tabs allow to verify if 609 (SD) or 709 (HD) matrices were used to encode component from RGB.
Note: The matrices are y = 0.213 * r + 0.715 * g + 0.072 * b for 709 and y = 0.299 * r + 0.587 * g + 0.114 * b for 601.

The red, green and blue tabs all should have the same luma value, if the correct matrices were used.

Note on monitors

Some aspects of the test chart may be detected by eye both on aligned video monitors and computer monitors. You should however be aware, that specifications of both type of monitors vary in different ways:

Note on waveform and vectorscope instruments

The primary purpose of the testchart is to measure its values digitally, with an eydroper tool. Some intelligence was used to layout the color patches in a way that the do not disturb each other too much on a waveform monitor, but the task was rather difficult.
An automatic analyzing programm may be provided at a later stage.

Copyright and Disclaimer

The HD test chart is provided "as-is" and without warranty of any kind, express, implied or otherwise, including without limitation, any warranty of merchandtabality for a particular purpose. In no event shall Belle Nuit Montage be liable for any special incidental, indirect or consequential damages of any kind, or any damages whatsoever resulting from loss of use, data or profits, wether or not advised of the possibility of damage, and on any theory of liability, arising out of or in connection with the use of this test chart.
Product specification are subject to change without notice and do not represent a commitment on the part of Belle Nuit Montage.

© Belle Nuit Montage / Matthias Bürcher January 2003. All rights reserved. Written in Switzerland.

Credits

I would kindly thank for their comments and suggestions: Jim Alfonse, Andre Brunger, Ueli Nüesch ande Michel Forbes.

History

1.12.3 1.2 new layout optimized for waveform, gray scale, charts for 720, PAL, NTSC and NTSC DV.

14.1.3 1.1 601/709 comparison tabs, wider ramps, corrections in documentation, PICT file removed

9.1.3 1.0