Click the above image for a Full Screen Rendering for newer browsers only.

Distribution permitted as long as the respective Copyrights are left intact and the color values left unretouched.

I created these bars out of necessity in that the world is lacking in correct and functional Calibration tools for Computer Graphics (CG). High end graphics creation programs like Adobe Photoshop, Video boards like Matrox Millenium and systems like SGI have what is called "Gamma Correction" built in however that correction needs to be referenced to the Viewing program that the rest of the world will be using, your internet browser, and only after your Monitor is adjusted correctly. If your system has none of the above referenced items then you can just skip ahead to the Monitor Adjustment part below.

Typically internet browsers and general image viewers like AcDsee or Lview Pro have null (no) gamma correction built in so when viewed through one of these programs an image will look as it would to the rest of the world, if there are no other "system" corrections, which is what 80% of all others will see. but if your video board or system has gamma correction and it is not set proper then what you percieve as your "just made work of art" might look less than that to others. If you fall into this group then you need to disable all gamma correction before monitor adjustment. If there are several interacting variable Gamma functions affecting the way an Image is produced or percieved then we need to break the system down into the individual parts, in the correct order, and adjust them Singly. The order would be Monitor, System, Video board and last but not least Graphics program. Your system does have the first, may have the second and/or third and probably has the forth but they must be isolated.

Perform this procedure to setup your monitor, then go through the calibration / gamma procedure on your system/video/graphics program in an isolated fashion and that order, using the above image to reference to without retouching your monitor adjustment. If your gamma correction is in an image editing program or is system level where it would recalculate the gamma of an image then the latter procedure would involve just loading this image and then saving it, under a different name so as not to corrupt the original, and verifying that the image levels have not changed any appreciable amount beyond the original. High end computers like Sun or SGI have, inherent in their OS, a system gamma function yet when an image created on the Iris is viewed on the Sun, Mac or PC the image is much too dark, conversely when created on the Sun and viewed on the Iris it is washed out. Paul Haberti has a page on this anomoly Here however he has not defined whether the aberation is caused by monitor misadjustment or an incorrect gamma function inherent in a system. In a week or two I will be back to an SGI indy and I will check out the problem then.

Alas the quick and easy procedure is as follows:
A monitor is properly adjusted when it meets two conditions. First, black should produce true black, to help maximize contrast. Second, white should produce the desired / proper intensity.
Typically there are 2 controls that we are concerned with:
Picture level / Contrast and Black level / Brightness.

IN PROCESS...............

The easiest way to adjust a monitor is to perform the following three steps in sequence: (1) turn the Picture control to minimum and display a black picture, (2) adjust the Black Level control to reproduce black correctly, then (3) adjust the Picture control to display the brightness level that you desire. and lastly there should be an even graduation of all the shades in between.

For the die hard details, Read the following:
There exist standards for video (NTSC, PAL, SECAM) calibration techniques however there is a strong differention between video and desktop graphics calibration requirements. There are also several standards for Color Bars - EIA, SMPTE, EBU, IBA, and BBC are the most dominant. Of these they have variations in Saturation and Amplitude which we wont go into here, what we are concerned with is the fact that color bars were designed to exploit the deficiencies of Video / Television transmission.
Typical modern color bars have 3 main parts to them, The main color bars, The duo toned blue areas (-I and +Q) with white between them in the lower left and the Pluge in the lower right. In video usage the transition between certain adjacent colors produces various anomolys such as dot crawl caused by NTSC interlacing or null (undefined color) areas because it takes up to the recipricol of the burst frequency, in time, for the next color to become valid, scanning from left to right. The dual blue areas were defined for a previously used and superior modulation technique that has been almost universally replaced by Y, R-Y, B-Y which is basically the same except for a slight equation and phase difference. They along with the Color of the main bars are used to set the Phase (Hue). Finally the Pluge area is there for Monitor level adjustment. Standard Pluge bars (3 small verticle bars) are grayscale bars at black -4 Ire, Black and Black +4 Ire.

Defining the needs of CG professionals, I have devised these bars. They are a modified version of the standard NTSC video pluge bars, Intended for all in one usage. The verticle Color bars themselves are all 100% Saturation with Amplitude and IRE being irrelevant. They and the dual blue areas are included for proper color balance, as in video, but they will not show up the dot crawl/ null anomolys as in video however in CG they do show the "dot pitch" spacing of your monitor, on very close examination and with a sharp monitor, ie: between green and magenta.

In the pluge area, Ire and blacker than black have no meaning in CG yet we need a similar function so I have placed a graduated gray scale from 81% to 99% K (black) in RGB steps of 4 out of 256. In addition I placed a dual set of dots, surrounding the scale and signifying the proper Black level (brightness) adjustment, which is total diminishment by that horizontal point of 93% black (16 RGB). My intent was to show one end of this bar bright enough for those that have monitors so far out of adjustment, to notice it, yet retain a resonably fine step. I also added a linear grayscale for at-a-glance gamma linarity ie: evenness through out the spectrum.

Charles Poynton's adjustment procedure He is the Rocket Scientist in regards to Gamma and Colour, Other pages on his site do get a little deep however he wrote the FAQs.

Copyright © 1996 Home Page All rights reserved.