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05/12/2014 07:02:38 AM · #1 |
Hello everyone,
I have been having a big issue with banding in my images and i'm not sure why.. I just did an image last night, in the dark using flash.. it was fine. Took it into Photoshop to edit, it was fine at first.. I wanted to darken up the background behind and around my subject. I used the Lasso tool and drew a selection around the subject, Inverted the selection, then I feathered the selection at 150px .... I then brought up my curves and pulled the mid tones down and BOOM, banding from hell... I was told once that you may see it happen in Photoshop but it doesn't always mean you will see it when you print. Today I printed an 11x14 of the image for an art show i'm entering in June and yep, banding in the image..
here's a web size copy of the image so you can see what i'm talking about:
image with banding
it's kind of hard to see on the web image.. but it's around my face.. around my arm reaching out.. and around the dryer door.
Yes it was an 8bit image, i've heard if you change the image over to a 16 bit image you can get away with more.. but once I save the image as a JPG, it automatically converts it to an 8 bit anyways so I didn't think that would help.
Anyone know why this is happen, and how I can stop it from happening?
Thank you for your help.
Message edited by author 2014-05-12 11:04:44. |
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05/12/2014 08:47:40 AM · #2 |
I'm not sure why that happens, though I've occasionally seen it. We have others on board here who are much more tuned-in to that sort of problem, and who hopefully weigh in.
But what *I* have to say is: "Why on EARTH aren't you entering our expert-editing challenges, dude?" The current one is "Winged Creatures" and it should be right up your alley :-) |
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05/12/2014 08:57:37 AM · #3 |
| hahha Bear_Music: I use to enter into the Challenges on here but there were so many damn rules I kept getting DQ'd on my entry's so I gave up entering.. |
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05/12/2014 09:13:05 AM · #4 |
Originally posted by Maver:
hahha Bear_Music: I use to enter into the Challenges on here but there were so many damn rules I kept getting DQ'd on my entry's so I gave up entering.. |
In "Expert Editing" you can't go wrong so long as every image you use was taken by you within the submission dates and you don't add text to your entry :-) It's wide open, pretty much. |
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05/12/2014 09:29:47 AM · #5 |
| maybe i'll partake in the wings one.. as long as I can find myself some wings to photograph. Thanks for the info.. it would be nice to get back in the competition game. |
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05/12/2014 09:39:31 AM · #6 |
Banding occurs when there are not enough distinct tones between the two "ends" of the area to form "invisible" bands.
For example, say you have a landscape with a fairly consistent bright sky, and you want to increase the degree of gradation. Let's also work in grayscale to make the example simpler ...
If the tonal value at the horizon is 5%, and at the top is 10%, you only have five-six tones to cover that area, and if it's too large each tone will take up a significant portion, possibly making it visible.
Sometimes then, when you try to increase the contrast with a Curve, you may extend the end of the range (to say 5%-15%) but you also may eliminate some of the intervening tones (e.g. you get areas of 5,7,9,11,13,15%) making the differences between the areas more visible. As you've found, the problem is even worse in the dark areas.
16-bit color gives you more possible shades between any two other colors, though I'm not sure whether the human eye can discern all those differences (mine can't, for sure).
Not sure this is the clearest explanation ... you might want to experiments by making some gradients with known endpoint values and applying various Curves to see what you get.
Message edited by author 2014-05-12 13:40:17. |
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05/12/2014 09:55:12 AM · #7 |
What Paul said.
Also, keep in mind that the difference between 8 bits per channel and 16 bits per channel is huge. For every tonal step available in 8-bit, there are 256 available in 16-bit.
A problem arises, however, when you go to print. If you are saving to JPEG to send to the printer, JPEG only supports 8 bits per channel. So you would need to use TIFF in order to retain the data.
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05/12/2014 10:12:24 AM · #8 |
Originally posted by kirbic:
If you are saving to JPEG to send to the printer, JPEG only supports 8 bits per channel. So you would need to use TIFF in order to retain the data. |
FWIW Costco supports 16-bit TIFF files -- I am sending some test images today. |
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