problems with gray scale transitiion

[sloow]

I'm trying to print a gray scale image that is intentionally blurry, and am finding the transition from white to black to be very stepped, chunky, terraced, scalloped, contoured, etc.(I don't quite know the right term). I'm printing with a z3100 44 inch.. I rendered the image in 16 bit, as I thought that might  have been the problem, printed with perceptual and relative colorimetric settings, gray ink set, color ink set. But It looks pretty much identical each time.

I'm printing on Moab 300 Entrada paper.

What am I overlooking?

thanks

[Tim Gray]

How does it look when you soft proof?

[Mark D Segal]

How did you do the colour to greyscale conversion? Do you have very steep curves? Is the tonal range compressed largely between the midtones and the shadows? In principle the z3100 can make excellent B&W prints (seen the results), but not owning one I don't know its settings to advise about how to manage the printer. I believe there are substantial resources on the internet covering this topic, however, so it may pay to do a web-search and make sure all your printer settings are correct.

[rdonson]

I'm trying to print a gray scale image that is intentionally blurry, and am finding the transition from white to black to be very stepped, chunky, terraced, scalloped, contoured, etc.(I don't quite know the right term). I'm printing with a z3100 44 inch.. I rendered the image in 16 bit, as I thought that might  have been the problem, printed with perceptual and relative colorimetric settings, gray ink set, color ink set. But It looks pretty much identical each time.

I'm printing on Moab 300 Entrada paper.

What am I overlooking?

thanks
[a href=\"index.php?act=findpost&pid=156802\"][{POST_SNAPBACK}][/a]

How are you using the print driver?  Here's how I print b&w:

[sloow]

The image is essentially a blurry two tone image, black and white. I went from the colour image, to gray scale, then made the curve very steep...so it was essentially black and white, then blurred it. It's the blurred areas where this phenomenon is occurring, no curves have been applied after the blur. A 100% view on screen reveals no contouring. I've been using application managed colour, which would mean Photoshop. I'm going to try the printer managed colour, and do a soft proof, as well as recalibrate the paper. Since I calibrated the paper a few weeks ago, winter has set in, (Montreal) it's cold outside and the heat is up high in the building where the printer is, making the studio very low humidity.. Seeing as this is fibre paper, it might be absorbing the ink very differently from the beginning of the month.


Will report back after more tests, thanks for your suggestions.

[sloow]

recalibrated the printer.. no difference,
in soft proof, there is a slight preview of the contouring, but not as much as in the final.
The problem is less severe using printer managed colour, printing in gray scale, at the expense of an increase in contrast.

cheers,

Paul

[DougMorgan]

Sounds to me like banding in photoshop and nothing really to do with the printer.

Though you may have the image mode set to 16 bit there are a number of operations done in 8 bits and the algorithms seem to be rather simple like the blur/gradient operations.  The solution is often to add noise.  Where to add it depends on the layout in photoshop but in general if you use a gradient or blurring on a mask you'll want to add 2-3% noise to the mask.   You can also add a mask to a layer and fill it with a small amount of noise in the problem areas to break up definite bands in areas like sky.  Without seeing the file I can't be more specific but I would give noise a try.

Good luck
Doug

[walter.sk]

The image is essentially a blurry two tone image, black and white. I went from the colour image, to gray scale, then made the curve very steep...so it was essentially black and white, then blurred it. It's the blurred areas where this phenomenon is occurring, no curves have been applied after the blur.
[a href=\"index.php?act=findpost&pid=156829\"][{POST_SNAPBACK}][/a]

I'm not clear on why you chose this particular way of printing a grayscale image.  On a new image file with white background, I make a rectangular selection, say 6x1 inches horizontally.  I reset the color picker to black & white, and then use the gradient tool set to Linear, drawing a line with the shift key down so that the gradient will go from one end of the selection to the other.  I get a smooth gradient from black to white.

I then make a second selection, equal in size to the first, directly under it.  This time I drage the gradient from the right side to the left, just to get the black & white reversed.

I then posterize the second gradient into an odd number of "colors", with no dithering.  This gives me a series of 3 steps, or up to 13, which I use for testing the neutrality and tonal range of the paper.  The top gradient is smooth, and can show banding, while the bottom gradient consists of discrete steps of tone..  You could even duplicate the horizontal gradients and rotate them 90 degrees to see if banding or blurring shows up in that orientation, as well.  I have never had the problem you describe on my Z3100.

So far, I have printed the tests in color, often embedded in a larger test image I use.  I have been thrilled with the accuracy  and neutrality of the Z3100 (I use Qimage to control the color, but you could use Photoshop, of course).  The papers I have used so far have been HP's Premium Glossy, Epson Premium Luster, Epson Enhanced Matte, Kodak Professional Glossy,  Bergger PN33 textured fine art paper,  and DigiPros Matte Canvas.

The printer-made profiles differ in how deep the black is that can be printed,  but not IN neutrality.

[BobDavid]

Sounds to me like quantization in the file and not a printer issue. Try adding between 1% to 3% random noise via PhotoShop filter to see if that takes care of the problem.

[sloow]

Thanks for the suggestions. I've tried adding noise, and that seems to help, but to get smooth transitions, I needed to go to 5 % which is a bit grainy looking on the final print. It also helped to switch to printing in gray scale. So we're getting closer. It seems to be that the transition points between the matte black ink and the gray and light grey aren't being handled so well.

Paul

[Mark D Segal]

As I said, I don't own a z3100 so I can't be helpful on the printer side of it. Perhaps there is a problem with the printer. Have you tested the printer by printing a greyscale test image? If not, I suggest looking over at NorthLight Images or Bill Atkinson's website. Both have greyscale printer test targets which you should download and print. That will help diagnose whether the problem is with your computer and printer or with your image. I.E. if the test image works well, then the problem is the image itself. If the test images don't print properly, then you need to look into the possibility that the printer, printer driver, etc. may be the cause.

The fact you are working in 16 bit should give you a strong measure of protection from banding and posterization. But it can still happen. Again, I would ask, what does the exposure look like? If you have most of the tonality congregated say in the left half of the histogram and then applied a steep curve to separate the tones, this can happen. Is that a possibility in this case?

[sloow]

I put a web page of a section of the image and the transformation I am working with here - Black and white banding, so you can see what I'm talking about.

The printer evaluation image demonstrates a smooth gradation, although more gradual, than the image I am trying to make.

I think the printer is working fine, so it's the way I'm making this image that isn't working.

thanks,
Paul

[kers]

I put a web page of a section of the image and the transformation I am working with here - Black and white banding, so you can see what I'm talking about.

The printer evaluation image demonstrates a smooth gradation, although more gradual, than the image I am trying to make.

I think the printer is working fine, so it's the way I'm making this image that isn't working.

thanks,
Paul
[a href=\"index.php?act=findpost&pid=158008\"][{POST_SNAPBACK}][/a]

It is exactly the problem I ran into myself...

probably you can already see the problem arising in photoshop using the preview mode with your profile.

My suggestion; find an other profile ( if you can)  that shows less banding in the preview mode and make a test if it works...