CurtPalme.com Home Theater Forum

[r3alsp33dy0ne]

Hi All,

Just bought an i1 Display LT to calibrate using HCFR. I've managed to get fantastic results for the greyscale but the primaries and secondaries are confusing me.

On my TV the colourspace is adjusted by varying the amount or red, green and blue for each of the primaries and secondaries. ie. I have RGB sliders for red, RGB sliders for blue, RGB sliders for green, and the same for all the secondaries.

When I adjust these I cant seem to get the x,y values for the primaries right. If x is correct then y is off and vice versa. Am I doing something wrong or is it just not possible to set the primaries correctly with this TV?

I can post the graphs from HCFR if it will be helpful. Any advice would be greatly appreciated.

[markhyams]

I have a Samsung A550, which uses the same CMS controls. I had to do quite a bit of tweaking to get my primaries and secondaries right. Varying the amounts of R G and B for each primary and secondary is not very intuitive. I got a feel for what is happening by playing with the color picker in photoshop. If you have it, you can take a color patch, and vary its hue, saturation and lightness and see what happens the the RGB values.

Mark

[sanlyn]

In order to use Samsung's CMS system with HCFR, you first have to give HCFR a reference to work with. The easiest reference is a reading from a 100% white test patch. Use the "Y" brightness value fom that reading to calculate the "Y" percentages for color patches of the primaries and secondaries (I use an excel spreadsheet with one cell set to the Y of white, and six other cells set to the proper % of white for whatever colkor space I'm working with. If your reference Y is from 100% white, be sure to use 100% color patches. If you want to use 75% color patches, take your reference reading from 75% white.

For instance, if your 100% white patch "Y" is 130.60 in HCFR, your final Red "Y" would be 22% of that figure (or whatever percentage is called for by the color space you're working with).

However, before trying to set your "Y", first try getting the current color into the right position on HCFR's CIE triangle. You'll find that the closer you get that little color ball to the correct CIE spot, the closer you're likely to get to your desired x,y for that color, as well as helping to later make the "Y" adjustment infinitely easier.

With your meter set for continuous readings, view the CIE chart while you have that Red 100% patch on your screen. In order to move Red UP or DOWN toward its correct CIE position, you have to add or subtract Green in your Red RGB adjustment. To move Red to the left or right, you have to add or subtract Blue in the Red correction panel. As you might be able to tell from this pattern, the correction required will be from the color that lies at the opposite end of the "line" along which you're trying to move. You might also note that as you get closer to red's CIE home base, your Red's Y will likely change along with the x,y coordinates. But don't try to correct Y until you get x,y squared away. This movement of the Red ball will get closer and closer to the proper x,y for Red. Don't be surprised if you can't get x or y EXACT -- you seldom can.

In some cases with many Samsung sets, there's no leeway for adding or subtracting the other two colors to move your color's ball exactly onto its spot. The A550 series is infamous for not being able to move Red at all, and Green is a tad too low from its own place. In that case, the best you'll be able to do is to let x,y stay as-is and move on to working with "Y". Anyway, errors with color brightness ("Y") are more obvious than are x,y errors.

With secondaries, remember to adjust the x,y of secondaries by first adjusting the secondary's opposite PRIMARY. For Magenta, the opposite primary is Green. Moving the G tab a few points is likely to get Magenta closer to its proper spot on the CIE triangle, or at least get it moving to the right height along that line. Adjusting the secondaries' opposite primary is usually the best place to start with secondaries. You're then left with balancing Magenta's main constituents, Red and Blue. If you look on HCFR's "Measurers" tab while you continuously read a Magenta patch, you'll see the left-hand height indicators for Red and Blue. Very likely, the Red and Blue bars are visibly out of balance, with one bar higher than the other. That'll give you a guide about the direction you need to take. Then look at the CIE chart and see whether Magenta is located closer to red or closer to blue:

For now, don't worry about the exact x,y numbers; the closer you get Magenta to its proper location, the more correct x,y will be. Let's say your "Measures" window shows that the red bar is higher than the blue bar (your magenta has more red than it has blue). Looking at the CIE chart, the magenta ball is closer to red than to blue. Conclusion: you need to lower red. This will bring the magenta ball closer to blue, and will lower the height of the Red bar on the Measures tab. After a while you'll be making finer and finer adjustments with both red and blue. Once you get the Magenta ball inside it's CIE "diamond", and once you get the red and blue bars close to the same height, your x and y will be pretty close to target. The last step will be to adjust Magenta's red and blue in roughly equal amounts to bring Magenta's Y into line, up or down.

First work with x,y. Then work with Y. Trying to adjust all of them at the same time is a great way to go bonkers fast.