[Luis Gabriel Gerena]

If I add say 20points to each RGB value I guess I should be able to get more light output while keeping the same ratio between the 3 colors...right? I know that at some point it won't work but at least I can get a little more out of my projector...any ideas?

 

[Brian Hampton]

Hi,


I'm sure each color will be affected to a different amount and your greyscale will suffer. So, I think it's not a good idea.


Besides, you may get better contrast by lowering bias instead of raising it.


Good Luck,


Brian

 

[ghibliss]

You did not mention which model projector you own!


Lamp based projectors all have spectral output limitations of one type or another. Halogen based lamps rapidly lose their Red output content in the first fifty hours or so. All projectors have a clipping point at which they can't make any additional light output for a given color. As a result you are never going to be able to maintain ratios like your theory outlines and have a proper Grayscale. By changing the Bias and or Gain values you will definitely alter the output characteristics which were calibrated to work with the gamma look-up table that is being used in the projector.


You may in fact be able to improve one point or another (Bias/Gain) but the overall change will most likely be worse than before you started.


Increasing light output is essentially what most of the manufacturers do with their factory calibrations. This is why the Whites typically clip and color temperature accuracy is completely ignored. Factory calibrated displays usually are way to Blue at the top end making color temperature excessively high, this is done to add brightness to the display and yield higher measured light output for the all important spec sheet.


You can certainly calibrate the projector to have a more accurate Grayscale within certain parameters of the projector. It is unlikely that you can substantially increase the light output while maintaining proper Grayscale. Improving contrast Ratio is generally improved most by the ability to reduce light output at Black (0 ire).


[This message has been edited by ghibliss (edited 07-03-2001).]


[This message has been edited by ghibliss (edited 07-03-2001).]

 

[Luis Gabriel Gerena]

I have the Sony VPL-W400Q

Here is an update: I did add the 20 points to each value and the difference is great! I am still tweaking it but preliminary results are that I get the same color temperature (well at least the color and hue seems the same) but much brighter images without the greenish cast that pumping the contrast creates. So, I have the same image but with a lot more punch..not bad for a simple tweak.

I know that all you said has some logic but still I am please so far with my results. There is a point where I couldn't get the image to match my original values in terms of color balance but I kept trying till I got the most from the projector while keeping the image just like the original but with more punch. Regarding the bias I didn't add the 20 points I lowered them since the bias increase by lowering the value as you know.

PS I know that the temperature is different now but since I can't tell of any difference in color balance I don't mind.