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Chromatic banding issue
- Thread starter Raxxis
- Start date
Compilla
New Member
With as vague a description of the issue you're having....
What Printer, What Rip, What media are you printing on?, profile, etc, etc
Stealth Ryder
New Member
YUP, good questions...
bob
It's better to have two hands than one glove.
Regardless of specifics, chromatic banding is most often an artifact from the dither algorithm. Try changing to the highest quality and concomitantly slowest dither method offered by whatever software you might be running.
bob
It's better to have two hands than one glove.
It occurs most often when you print a large gradient or a bitmap that's created from a gradient. Instead of a smooth transition from shade to shade the gradient shows distinct steps of color that really have no business being where they are on the gradient. This is different from seeing fountain fill steps in a coarsely specified gradient.
When printing a gradient that's too coarse the bands are regular and of the proper color. Chromatic banding appears generally appears as bands of slightly darker and seemingly unrelated color willy-nilly without any rhyme or reason.
As previously noted this sort of banding seems to be an artifact of the dither algorithm. At any rate, selected a higher quality dither method more often than not either cures the problem or mitigates it to a point where you can live with it.
Banding can be classified into 3 main types:
1) Chromatic Banding (aka as directional banding, lawnmower effect): Chromatic banding is the most typical form of banding in piezo inkjet printers. It takes it’s form as a series of alternating color shifts from light to dark. It occurs most often when printing in bidirectional modes and is due to the change in the order that ink is laid down from one pass to the next.
2) Banding due to incorrect Step Adjust (Distance Banding): Step adjust is the most common type of banding to users who are new to the product. Media is fed through the printer using a grit roller assembly and a series of pressure rollers which hold the media to the grit roller. All medias have a different composition and are gripped differently by the grit roller. Some medias are soft and grip well. Others are hard and smooth and may slip slightly when being fed through the printer. If a media ‘slips’ it will not feed far enough. This will cause dark overlap lines to appear at the junction of every print pass. The default distance adjust setting on the printer is 100.00% so to correct this problem the value needs to be changed to a larger number, 100.25% for example. The opposite of this would be a media that grips very well and actually moves through the printer at a faster rate than anticipated. The result of this would be a white space (lack of ink) at the junction of every print pass. The correction for this condition would be to lower distance adjust value, for example changing the value from 100.00% to 99.85%.
3) Dot Gain Banding: Dot gain banding is a problem that can occur on a solvent printer due to it’s ability to print on uncoated materials. Outside of the solvent world, inkjet printers print with water based inks onto specially coated materials. These coatings are designed to dry the ink at the perfect rate to create or ‘control’ the size and shape of the dot. In the last few years these coatings have become so advanced that many ink jet printers can produce near photo quality output. Back in the solvent world however, the idea is to print on standard uncoated materials. Uncoated materials are much, much cheaper and are designed to withstand the outside elements of the world. With no special coatings to control the dot size or ‘dot gain’ another method of controlling the ink is needed. The most obvious of these is heat. The more heat you can apply to the ink the faster it will dry, the more control you have over the final dot size. Dot gain banding is most noticeable in dark, solid fill colors and it the shadow areas of photo images where larger amount of ink are printed and is a result of the bleeding together at the junction of each printer pass. Dot gain banding can be controlled by finding the optimum temperature settings for the media being printed on and also by ensuring the proper linearization and profile for the media