Color noise/dithering with MacPro DVI output
Hello everybody,
to describe my problem/question I have to give you some additional information.
I am working for a company that produces KVM extenders. One of our products is an digital extender system which enables the transmission of standard computer signals (keyboard, video, mouse) via CAT cable over distances up to 140 meters.
In combination with a MacPro (MacPro 4,1, Mac OS X 10.6.5), this extender shows some "peculiarities" when transmitting images.
The mouse does not move properly at our receiver module; the cursor stutters at the screen.
In this constellation, however, almost the complete bandwidth is required for image transmission. In order to generally avoid this problem, we use a compression procedure to transmit data. Usually, only image changes instead of full images are transmitted. This method saves bandwidth and results in a stutter-free image. In our case, the compression procedure cannot be applied due to the fact that the MacPro constantly displays a stuttering image.
In order to clarify this problem we have done some research which I am going to explain in the following.
The tested graphics cards (ATI Radeon HD 4870 and GeForce GT 120) do not provide static screen content at the digital DVI output, but create a constant image/color noise/dithering.
Since the compression procedure cannot be applied (only full images are transmitted), the performance at higher resolutions is rather low. This is especially inconvenient for the user because this failure is invisible/irreproducible and there seems to be no possibility to disable this color noise.
In order to make the color noise visible, we used a screen-capture tool to produce several images of a standard desktop of a Mac OS X installation.
We took a closer look at these images and realized that the green background does not consist of one RGB color value, but of slightly deviating color values. In order to highlight the different color values, we used a graphic tool and colored the color values with more differing colors.
Now the color noise is clearly visible. When we looked at the same image with a delay in time, we realized that the color noise was not static but seemed to appear rather randomly. The colors deviate and a stuttering image is displayed!
The crosscheck against a background without color (white) shows that the color noise does not occur and the image performance of our extenders has evidently improved.
Now my actual question:
Does anyone know how to disable this dithering within Mac OS X?
Thank you in advance for taking the time to read this and maybe give me some hinds to solve the problem.
to describe my problem/question I have to give you some additional information.
I am working for a company that produces KVM extenders. One of our products is an digital extender system which enables the transmission of standard computer signals (keyboard, video, mouse) via CAT cable over distances up to 140 meters.
In combination with a MacPro (MacPro 4,1, Mac OS X 10.6.5), this extender shows some "peculiarities" when transmitting images.
The mouse does not move properly at our receiver module; the cursor stutters at the screen.
In this constellation, however, almost the complete bandwidth is required for image transmission. In order to generally avoid this problem, we use a compression procedure to transmit data. Usually, only image changes instead of full images are transmitted. This method saves bandwidth and results in a stutter-free image. In our case, the compression procedure cannot be applied due to the fact that the MacPro constantly displays a stuttering image.
In order to clarify this problem we have done some research which I am going to explain in the following.
The tested graphics cards (ATI Radeon HD 4870 and GeForce GT 120) do not provide static screen content at the digital DVI output, but create a constant image/color noise/dithering.
Since the compression procedure cannot be applied (only full images are transmitted), the performance at higher resolutions is rather low. This is especially inconvenient for the user because this failure is invisible/irreproducible and there seems to be no possibility to disable this color noise.
In order to make the color noise visible, we used a screen-capture tool to produce several images of a standard desktop of a Mac OS X installation.
We took a closer look at these images and realized that the green background does not consist of one RGB color value, but of slightly deviating color values. In order to highlight the different color values, we used a graphic tool and colored the color values with more differing colors.
Now the color noise is clearly visible. When we looked at the same image with a delay in time, we realized that the color noise was not static but seemed to appear rather randomly. The colors deviate and a stuttering image is displayed!
The crosscheck against a background without color (white) shows that the color noise does not occur and the image performance of our extenders has evidently improved.
Now my actual question:
Does anyone know how to disable this dithering within Mac OS X?
Thank you in advance for taking the time to read this and maybe give me some hinds to solve the problem.
MacPro, -