|Originally posted by scotthorton
1: Can the OpticOne package do as good a job as CF on measuring and producing end-results?
And 2: I read it’s (OpticOne) manual, it looked a little overwhelming. It has ton’s of info, but no real directions on exactly what to do as far as I could see. Can a novice use it effectively?
Input and suggestions very welcome. Cheers, Scott
Both Colorfacts and OpticOne using their respective trichormat sensors will yield equally accurate calibrations.
The Eye-One sensor (a spectroradiometer) has one advantage over the trichromat sensors. It can read directly from the screen, and thus can take any coloration imparted by the screen (I'm talking front projection here) into account in the calibration. The trichromats can't. They are designed to be pointed at the PJ. If you use a color accurate screen, like a Stewart, you don't need to read from the screen, IMO.
The Eye-One has some disadvantages in comparison with the tri-chromats, especially in the areas of speed, usability, and accuracy when measuring low IRE's. Several folks I've spoken with who own both sensors, only use the trichromat sensor. If I were buying Colorfacts, I would buy the Colorfacts trichromat sensor, not the Eye-One. If you are willing to spring for both types of sensors, use the Eye-One to set the PJ to D65 by reading directly from the screen at 80 IRE (the Eye-One is very accurate at high brightness levels). Then use the trichromat to read the calibrated 80 IRE directly from the PJ. You can tell Colorfacts that this is D65, regardless of what the trichromat is reading, and Colorfacts will derive the appropriate correction factor so that you can then use the Trichromat sensor to calibrate the whole grayscale to the same x,y color coordinates that it read at 80 IRE. The same technique can be used with a spectroradiometer and OpticOne, also.
As far as how the two trichromat sensors compare to each other, they are not identical, but they are very similar. They use the same filter set, which largely determines how accurate they are with a variety of light sources. The Optic One sensor responds to calibration changes instantly. The Colorfacts sensor takes several seconds to respond. IMO, the most significant difference between Colorfacts and OpticOne is the price.
Both systems require an understanding of color science and calibration techniques. One of the best sources of practical info on this can be found on the Smart III website: http://www.smartavtweaks.com/Dummies3.html
You will find a practical step by step procedure for performing calibrations and the basic color science behind it. Colorfacts also has articles on color science and calibrations which are helpful.
Posted below is a step by step procedure written by forum member, Htomei, for calibrating an SP7200 with an older version of Colorfacts and Avia. He wrote this as a memory jogger for his own use. It contains specific terminology referencing commands in Colorfacts, Avia, and the SP7200's menu. That part of the instructions might be confusing if you are not familiar with the Colorfacts, Avia, and SP7200's menus. However, the particular method that HTomei describes can be applied to any PJ and calibration system. After reading the material on the websites referenced above, the procedure below will make more sense.
There are two key elements. The first involves establishing the PJ's limiting color, and determining the limiting color's maximum effective Gain setting at 100 IRE. This Gain setting is used as a constant when adjusting the Gains. The second key involves determining the extinguishment points for R,G,and B at Black. The Green Bias setting that creates extinguishment at Black is used as a constant when setting the Bias/Offset controls.
SETTING THE BASIC SETTINGS WITH AVIA:
1. SET FOCUS:
2. SET BRIGHTNESS & CONTRAST:
- Set PJ to 4:3 display mode
Either: Avia / Title / Advanced Avia / Basic Patterns / Black Bars; then,
When dithering is eliminated you will still be able to see both moving dark grey bars in the pattern
Or: Avia / Title / Advanced Avia / Video Test Patterns / Greyscale Levels /
Window Patterns / 0 IRE; then, Lower brightness until dithering just disappears (side bars act as a point of reference for black, or lack of dithering). Looking at border between black bars and the 4:3 image will make it easier to see when dithering disappears
- Avia / Title / Advanced Avia / Basic Patterns / Needle Pulse
- Right bar should be barely visible; (this will be fine tuned later
by setting the Gains)
3. SET COLOR SATURATION & HUE:
- Avia / Title / Advanced Avia / Basic Patterns / Blue Bars
- 7200 / Picture / Color
- With blue filter over eye, flashing & solid boxes should appear same
- With blue filter over eye, hue (tint) inner two boxes should disappear
4. AIM COLORIMETER:
- Avia / Title /Advanced Avia / Video Test Patterns / Grey Scale & Levels /
- Set to 40 IRE and pause if possible
- Colorfacts / Continuous Reading / “Blow up” RGB Levels Bar Graph
-Colorfacts / Luminance Meter
- Move sensor until it ‘maxes out’
- Go down to 30, then 20 to see if enough light on RGB Levels Bar Graph
5. SET GREY SCALE (COLOR CALIBRATION):
- Avia / Title / Advanced Avia / Video Test Patterns / Greyscale & Levels /
- Set Gains & Offsets as described below
Colorfacts Calibration Steps
1. Put Colorfacts into “Continuous Measuring” and view the “RGB Device”. In Avia, select the 100 IRE window pattern. Determine the limiting color (R G or B?) by raising each color’s “Gain” on the PJ in succession to the point where it stops affecting the “RGB Device”. Lower the Gain setting back one step to the last setting that had an effect on the RGB Device when that color’s Gain was raised. After doing this, the color which is the lowest on the RGB Device is the “limiting color”.
2. We are going to set the RGB Gains using an 80 IRE window pattern. We are going to set the RGB Offsets (or Bias or Cutoffs) with a 30 IRE or 40 IRE window pattern. (Use the dimmest window pattern that is still bright enough for the meter to read accurately).
3. In Avia, select the 80 IRE window; use Colorfacts RGB Device to balance RG&B by adjusting the gain only on the two non-limiting colors. Don’t change the setting of the limiting color. It is already set to highest setting that will still result in D65 at 100 IRE. (In doing this, the Contrast setting gets fine-tuned as referenced above.)
4. In Avia, select the 30 or 40 IRE window. (Use the dimmest window pattern that is still bright enough for the meter to read accurately). Adjust the Red & Blue Offsets (Bias or Offsets) controls to balance out the colors on Colorfact’s RGB Device. Don’t change the Green Bias setting. (Back when we set the Brightness, we were mainly setting the Green Bias.)
5. Recheck color balance at 80 IRE because adjusting Gains or Offsets can effect the other. Recheck the Contrast and Brightness settings.
6. Do a grey scale run from 0-100 IRE.
- Take out of continuous reading into single reading
- Measure / Greyscale Wizard / Window Pattern 0 IRE (Black) / Run through 10, 20, etc. to 100 IRE