Blue Sky Banding

[openspace]

I have a number of digital images with crystal blue skies that intermittently exibit faint white banding in the sky when I print them. The banding is not visible on my monitor at any magnification. The bands are printed parallel to the movement of the inkjets.

I have heard that Canon, Epson and HP printers all produce this effect, especially with blue skies. I have has some success removing or minimizing the banding by adding 2% noise to the sky and increasing resolution of the image to 300dpi and above. I always print with a printer resolution of 2400x1200dpi.

I also understand that banding may be the result of minute degradations caused by image manipulation (contrast, saturation enhancements, USM).

What I want to know is has anyone figured out a surefire way in Photoshop to eliminate this banding problem?

[w10d]

Depends on the cause of the banding:

1) Printer gamut not large enough - 6 or 7 colour ink printers are less prone to this sort of problem, I have'nt experienced this at all with an Epson 2100, and it was rare on a 1270, certainly not on a typical sky. (You don't mention the printer you are using - but your description sounds like a printer issue).

2) Caused by excessive Photoshopping: Start out in 16 bit, and try to avoid Levels/Curves type manipulations after moving to 8 bit, check the Histograms, (esp. blue channel in this case).

PS 8 bit files should'nt exhibit this kind of problem with 'normal' manipulation, as you mention, adding noise will help mask banding.

[dtrayers]

Edit: W10D beat me to it.

If the banding is due to posterization as a result of over manipulating an 8-bit image, the only solution is to work in 16-bit mode. The book Real World Photoshop is an excellent resouce for this topic. I'm sure there's a lot of web-based articles too.

But you post said that the bands are "parallel to the movement of the inkjets". If they're in a straight line, then you may have a printer issue, not a posterization issue. Check you paper settings. If you have a Canon, check that the print quality is set to high and the halftoning is set to diffusion.

[John_T]

...and check that your computer has enough RAM. Print files can be quite large, and if it is being shoveled in small pieces from the hard drive banding can occur.

[pwagner]

Rotate the image 90 degrees in Photoshop (or whatever software) and print again. This will help you determine if it has something to do with the pixels of the image or with the way the print heads are working (or not working, as the case may be).

[openspace]

All great suggestions.

To answer a few of your questions, I print with a HP 970CSE on both HP Premium Plus matte and glossy papers. It is only a 4 color / 2 cartridge ink system, but the prints it produces are spectacular, tack sharp and vibrant - good enough that I'm showing and selling in galleries.

The only problem I have had is with the occasional unbroken clear blue sky, especially skies that exhibit any kind of color gradient - see attached compressed sRGB JPEG image for an example.

All images are currently processed in the AdobeRGB color space primarily as uncompressed 8-bit TIFFS converted from RAW. Although this may be where my problem lies - that is until Photoshop CS arrives next week - the histograms of the processed original are smooth and the original shows remarkably little posterization on screen even when magnified to 1600% at a screen resolution of 1152x864.

Rotating the image in PS has no effect on the banding. Nor are the bands always in the same place in the sky. the lines are not sharp (blocked jet). They are diffuse, usually 1/4 inch wide, extending from top to bottom of the sky and really only noticeable under bright light. The effect is more pronounced on matte paper.

Processing power, RAM and video quality are not issues - P4 2.4GHz 800MHz FSB, 512 MB DDR RAM. 64MB AGP 8x Nvidia GeForce. Monitor is color calibrated with Eye-One.

We'll see what moving to a 16-bit workspace does. Thanks for the help.


http://www.iaspd.org/images/dc2.jpg

[John_T]

Ok. I had that printer, the 970Csi, up until about six months ago. I found that even the cheaper 5550 with photo cartridge was better for photos, but since I got the Canon BJCi9100 everything HP looks very inferior, including the papers. Rapid fading through both ink and papers. In a year or even less, you may start getting complaints from your customers.

I would suggest that your banding is a printer/printer driver issue that the blue skies are accentuating. It was always there but not pronounced enough to attract your attention. Subtle things.

If you are selling your prints, I would definitely look at getting a high quality Canon or Epson printer. And while you are at it, get a Matrox graphics card.

Your photo is excellent!

[w10d]

After reading your update I'd agree with John - this sounds like a printer issue, going to 16 bit will do nothing to help as the printer is unable to reproduce continuous tone in 8 bit, especially in blues (which CMYK is notoriously weak on). This is why the 'photo' printers employ 6 or 7 inks instead of 4, the addition of Light Cyan, Light Magenta (and in the Epson 2100/2200 Light Black) increases the range of tones the printer can reproduce.

I would also agree that if you are selling your prints you should look carefully at their archival qualities.

[openspace]

Thanks, John.

I have been very impressed with the quality my 970CSE has provided. I do worry about the fading issue. According to HP, the Premium Plus paper will resist fading up to 17 years even with the 970CSE inks.

But then again, they're a big corporation looking to sell product. I am looking at the i9100 as well.

[John_T]

*- rant mode on -*

Frankly, after I got the i9100 I became somewhat disgusted with HP. I took an 8X loupe and looked at the HP prints and then the Canon prints. HP cheats like crazy with Disney colors and pushed "definition", meant to give a striking impression for home and family users. I found that on some HP prints that I had given someone in an industrial area, the blacks were turning brown from air polution. And some others quickly got discoloration streaks from lying in the sun.

I also thought I could use up left over HP paper with the Canon. No deal. The Canon inks splotch, speckle and clot on HP glossy. Sorry, but for me HP is strictly for the amateur home user splash. I used HP for years with my computer for multiple purposes while I was shooting film and getting lab prints. When I started digital with the HP, I too was impressed with what I could do myself, but slowly I began to see the cheats and limitations. The i9100 blew the rest of any illusions about HP out the window.

To be fair, HP has their markets as a business and home marketer and manufacturer, whereas Canon and Epson are more in the image processing business. At some point we all cross the line from consumers to image creators and the whole game changes.

*- rant mode off -*

[openspace]

Yea, I have heard the i9100, as well as the Epson 2200 systems are excellent, and I am looking into both. But to be fair to HP, my monitor is color profiled with Eye-One and everything that comes off my HP has precisely matched the monitor image.

I, too have examined my HP prints with a loupe, and there are indeed individual pixels mixed throughout that seem punched (what you call Disney colors), but overall when viewed with the naked eye, the color rendition has been excellent. No super saturation, no punched definitions. I have also seen the same with my friend's Epson 2200 prints though.

As a photographer, I tend to be a purist. Sure, we all "cheat" a little with our polarizers, 81A's and graduated NDs in an effort to accurately capture what our eye sees. But that is the point - capturing what our eye sees, not what we wish we saw.

I loathe those who use digital techniques to alter their images by saturating colors that were not in the original, that alter natural features with airbrushes, or worst of all cut and paste the best parts of multiple images together into one unforgettable, but in reality, unphotographable scene. Anybody can take a crappy photo and using a computer make it look great. But it is those that strive to capture only what their eyes see, that accept the limitations of nature, that use the lens and not the computer to capture the great shot that I admire.

And that is what I am looking for in a printer. It has to accurately capture exactly what I saw, what is on my monitor or on my slide. And the print has to last.

I will admit your comments have made me nervous. I am having nightmares of images on my client's walls fading or color shifting. But I haven't seen it with my own prints. In fact, now I have several on the dash of my car. I live at 8600 feet in the Rocky Mountains. Our sun is piercing, and the UV radiation is off the charts. If they can survive on my dash, they'll probably survive on my client's walls. So far, so good. I'll keep you posted.

[John_T]

I agree with your tastes in photography and prints. That is what I go for and my whole system is set up to carry reality from camera to print, storage or upload. But what I see mostly now in so-called top photos on top sites are more and more LSD induced illusions, perversions of reality. And stranger still, this seems to be what many people want. I've always found simple reality more beautiful than dreams, or in some instances, outright nightmares.

Sorry I made you nervous, but I've been through the wringer on the longevity issue for all kinds of media and content. I have also marketed a good number of computer products and know what I paid for favorable "independent" reviews and test reports. I know what I've paid wining and dining and backhanding technical editors and having my arm twisted to advertise in a publication to get favorable reviews. And I also know that when there are millions and billions in markets for a particular product type, how heavy the heavy players can play and how much influence they can exert on those who influence the sale of their products. I have no illusions about their honesty, morals or ethics. And when the products don't turn out to be what sales and the "experts" promised, you call up to find that the former sales VP who was so effusive and convinced of his products is now a janitor somewhere and you are put on hold for one of their expensive big-time lawyers who will "take care of" your complaints.

Don't worry about your prints. You have acted responsibly in the interests of your customers, but your responsibility ends there. If someone has a complaint, the best way to win friends and influence new sales is to send them a new print on the latest medium, without hesitation or charge, along with a big smile. Don't even waste your time asking where the old print was hung, but you could print up a slip describing the best conditions for displaying your prints and enclose it with every order. Preventive medicine.

[openspace]

Amen to all you wrote. We are a society addicted to instant gratification. There is magnificent beauty to be found in the natural world. But to capture that perfect moment, the perfect image, the perfect sunset, the perfect bloom you have to be patient to see it, and precise to capture it. And that doesn't sit well with a society that wants it all, and wants it now.

Too many photographers are trading in their artistic credentials for cheap computer trickery, and we all suffer as a result. It is true, few customers these days care about the process, about the blood, sweat and tears we shed to capture truly great images. All they care about is the product.

But as the image maker, I still have to face myself in the morning. I value great images and the great men and women who work for them, and I won't use my computer to fabricate lies. It's nice to know there are others who share the same conviction.

Ok. Enough ranting. One question...

What paper works best with your i9100?

[John_T]

Ha! What paper?

Right now I am using Canon, Ilford and Tetenal. All are excellent, depending on the content. I just did some candid portraits of children on Ilford Smooth Fine Art Paper. Stunning in their naturalness and softness. They live, breathe and have an intimacy you won't see on gloss or matt.

What I love about the printer is it's ability to render perfectly to each paper. It is good to get the profile for the paper from the manufacturer.

http://www.ilford.com/html/us_english/homeng.html

http://www.tetenal.com/f_uk1.htm