wrong component output colour on multibridge extreme

[Michael D]

Hello Gene.

I always thought that a lack of numerical precision was a potential cause of what I am experiencing. The spikes and missing data that I described as occurring in the red and green channels look like the artifacts in the conversion between Y

[Michael D]

Hello Gene,

For completeness, I am including the mean values of luma, red, green, and blue for a black and white file I captured using the DeckLink Pro card. I will limit my observations to a clip which I have labeled home.mov. As I previously stated, Blackmagic initially suggested I apply a black and white filter to the black and white files that exhibited the green tint. I applied the black and white file to home.mov within Premiere Pro and labeled the resulting clip homeprime.mov.

The mean values of the histograms of luma, red, green, and blue of a frame from home.mov with the DeckLink Pro card and drivers installed were 171, 172, 173, and 162, respectively. The red and green channels exhibited spikes and missing data. The gain of the blue channel was low and the clip had a green tint when viewed on the computer monitor and when viewed on the JVC monitor using the component out of the card. The green tint was much reduced when the clip was viewed on the JVC monitor using the composite out of the card.

The mean values of the histograms of luma, red, green, and blue of the same frame from homeprime.mov with the card and drivers installed were 170, 171, 170, and 170, respectively. All the channels now exhibited spikes and missing data. The clip appeared black and white when viewed on the computer monitor. The clip may have exhibited a very slight, almost undetectable green tint when viewed on the JVC monitor through the component out of the card (this may be the tint that is potentially inherent in CRT monitors that you and Bob Zelin mentioned). The clip appeared black and white when viewed on the JVC monitor through the composite of the card. Note that I could accomplish the same result as the black and white filter within Premiere Pro simply by increasing the gain of the blue channel within the After Effects plugin version of Color Finesse.

Now for some data with the drivers removed, the DeckLink Pro card physically removed, and the standalone Blackmagic codecs installed. The mean values of the histograms for luma, red, green, and blue for the clip home.mov were 164, 163, 165, and 162, respectively. The histograms did not exhibit spikes or missing data and the clip appeared black and white on the computer monitor.

The mean values of the histograms for luma, red, green, and blue for the clip homeprime.mov were 163, 162, 162, and 170, respectively. All of the channels exhibited spikes and missing data. The gain of the blue gain was greater than the gain of the red and green channels and the clip now appeared to have a blue tint on the computer monitor.

With the card and drivers in the system, the black and white files had to be color corrected by applying a black and white filter (think about the irony of that) which basically increased the gain of the blue channel. However, with the card and drivers removed, the gain of the blue channel was greater than the gain of the red and green channels and the clip now had a blue tint.

The tint I see on the black and white files is a function of potential inaccuracies in the gain of the red, green, and blue channels. The green tint I see has nothing to do with the JVC monitor (or any inherent almost undetectable tint due to the nature of CRTs).

Let me know your thoughts after you have a chance to review all this data. I feel that Blackmagic support has to step up to the plate and investigate whether there is any merit to the results of my analysis. I am aware of the problem and have developed a viable work around. You can

[Michael D]

Hello Gene,

I see that you are back from vacation. I was wondering if you reviewed my two posts on 11 and 12 June in response to your last one on 10 June. I was hoping you would have further input and interest in this anomaly.

Michael.