The HardingFPA includes visual information in addition to the results images in the form of Frame Masks. These mask images are overlaid on top of the frame images on the large image in the top-left of the main screen and depict the locations of problem areas in the sequence, to aid in the repair of failing sequences.
When the results first appear on the graph, the large image in the top left hand side will appear as usual. In order to utilise the frame mask images, Click on the Frame Mask menu, and select the type of failure that you want to see the mask overlaid for:
When any of the frame masks are chosen from this box, the images will change and the mask will be overlaid onto a darkened, black-and-white (monochrome) version of the original frame image. A frame will appear around the image to depict the currently selected mask. An example is shown below:
The colours represent the number of transitions which each pixel has experienced in the most recent second after allowing for motion. The analyser will issue a failure when more than one quarter of the image contains red or purple pixels. The same colour coding (shown below) is used for both luminance and red flash analysis.
Pixel Colour |
Number of Transitions |
none |
0 |
green |
1 or 2 |
yellow |
3 or 4 |
orange |
5 or 6 |
red |
7 or 8 |
purple |
9 or more |
The spatial pattern mask data logs the activity which exceeds the spatial guideline limits as shown below.
The mask data appears as a set of uniformly coloured tiles in the image which represent how long they have persisted in the image sequence. Spatial mask data only appears for stationary, regular patterns which lead to failure. Any spatial patterns which drift, or are not regular, or do not persist in the video long enough to trigger a failure are excluded.
Pixel Colour |
Persistence |
none |
no regular stationary pattern present |
green |
0 to 1/6 second |
yellow |
1/6 to 1/3 second |
orange |
1/3 to 1/2 second |
red |
more than 1/2 second = FAILURE |
purple |
outside of pattern regularity limit |
The actual colours used represent how close the spatial pattern is to causing a failure rated in terms of how long the pattern has persisted in the image sequence. When running under Ofcom guidelines, the HardingFPA will only tolerate illegal spatial patterns to persist for up to half a second -- any longer than this will lead to a failure. Therefore the green, yellow and orange colours denote the build up to failure while red represents the actual failure itself. Purple is reserved for tiles which are part of the detected spatial pattern but whose pattern characteristics lie outside of the allowable range when compared with the rest of the spatial region. These purple tiles do not represent persistence and can accompany spatial masks of any colour.
It is important to note that the HardingFPA only presents mask colours for pixels which will go into failure. This allows the editor to focus on the region(s) of the image which lead to the failure rather than flooding the user with unnecessary information. As a result, many images will contain no masked / coloured pixels even though there may be some flash or pattern activity occurring.
In addition, frame mask activity may suddenly disappear after an isolated failure sequence if the remaining pixel transition activity does not lead to a subsequent failure.