Some Questions - DPChallenge Forums

Sony 16-50mm f/3.5-5.6 E-mount

08/01/2002 12:01:50 PM · #1

Banding
Took pictures yesterday, sunny day and bright blue sky. One of them I cropped into a final image that I liked. Problem is the sky is a significant component of it and it has banding. If the sky would not have been so bright, the image would have been very flat. What could I have done to avoid that banding? Polarizer filter? What could I do without additional accessories?

Rules - What's allowed?
Levels, curves, hue/saturation I always do as adjustment layers since that is non destructive. Is it allowable however to do any of the following:

a) Set the blending mode of any of these adjustment layers to anything other than "normal"?

b) Can I dup the orig image, do any of the above adjustments and set that layer to say "overlay"?

In my mind, a) should be allowable but b) veers towards manipulation as in essence you would be working with two negatives, so to speak. Would like to have feedback on this as to what falls within the rules. Thanks!

jmsetzler

Sony Alpha a6000

08/01/2002 12:19:52 PM · #2

Unfortunately, layering is not allowed...

I don't think I have ever had a problem with banding in a sky portion of an image... what resolution is your camera and what mode are you shooting it?

Nikon AF-S DX Zoom-Nikkor 17-55mm f/2.8G IF-ED

08/01/2002 03:14:13 PM · #3

Thanks for the clarification.

I'm shooting at 1280x960, the highest available on the Mavica. Shots were made in "landscape" mode at various distance settings.

spiderman

Canon EOS-D60

08/01/2002 03:56:16 PM · #4

I''m shooting my D60 at its highest JPG resolution (3072x2048)

the only time i''ve seen banding is post-shot - in PhotoShop 6, by shrinking the image size, I''ve had nice blue skies become "targets", with distinct areas of varying shades of blue

the only thing I can think of (and I''m no expert, so this is just wild conjecture) is that the compression of data throws out the intermediate values, leaving the bands --- so since your camera records images in JPG format, it might be a matter of how much compression (if any) it performs

***** I just d/l the mavica manual ***** it says that in normal mode, it will record 6 pictures onto a floppy --- that sounds like it''s doing at least a 9/12 compression to me (if 12 = none, then 9 = "some")

* This message has been edited by the author on 8/1/2002 4:05:55 PM.

hokie

Nikon D2X

08/01/2002 04:03:47 PM · #5

That banding is usually a result of low resolution where the amount of pixels get blocky due to not enough variaion of very small gradients....I am stumped.

Hey spidey;

How do you like that D-60? Have you shot with a lot of auto-focus film?

I am curious about the auto focus character of the D-60.

Also, Does the D-60 ever exhibit moire in any shots for you..another concern?

I have a few Nikon lenses but nothing in the Nikon DSLR line interests me as much as the D-60/D1 of Canon.

jmsetzler

Sony Alpha a6000

Sony 16-50mm f/3.5-5.6 E-mount

08/01/2002 04:04:28 PM · #6

I was thinking the same thing, but since Journey was talking about layering and other more advanced features of PS, I didn't assume that this may be an issue...

welcher

Canon EF 70-200mm f/4.0L USM

08/01/2002 04:12:23 PM · #7

The banding is almost certainly related to compression, and not to resolution. The way compression works is to "average" pixels over a range of neighboring pixels. If that range is very slightly graduated, it'll all come out as one color, until the scales are tipped enough towards another color, then you'll have a range all that color.

Only way around it is to back off the compression.

hokie

Nikon D2X

Nikon AF-S DX Zoom-Nikkor 17-55mm f/2.8G IF-ED

08/01/2002 04:22:35 PM · #8

Originally posted by welcher:
The banding is almost certainly related to compression, and not to resolution. The way compression works is to "average" pixels over a range of neighboring pixels. If that range is very slightly graduated, it'll all come out as one color, until the scales are tipped enough towards another color, then you'll have a range all that color.

Only way around it is to back off the compression.

Exactly Welcher..I guess I was assuming he had banding in the original before compression or other editing.

But you are right, high compression can do this as well.

GeneralE

Canon PowerShot S3 IS

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

08/01/2002 04:30:37 PM · #9

It might be possible to increase the contrast range in the affected area (with curves or levels) before compression to reduce the problem, as long it doesn't too adversely affect the rest of the photo.Another possibility would be to try adjusting just one or two of the color channels independently to see if that area can be improved with messing up the rest.

welcher

Canon EF 70-200mm f/4.0L USM

08/01/2002 04:38:17 PM · #10

Originally posted by hokie:
Exactly Welcher..I guess I was assuming he had banding in the original before compression or other editing.

But you are right, high compression can do this as well.

I think you assumed correctly. I don't know much about his camera, but it wouldn't suprise me to find that it either compresses significantly by default, or that he's got it set to do so manually.

floyd

Canon EF 17-40mm f/4.0L USM

08/01/2002 05:21:49 PM · #11

While I agree that this might be down to compression it could also be down to colour reduction. If you take a high-colour image and reduce the number of colours to, say, 256 then under some circumstances you get the kind of banding being described. Many graphics packages (Adobe ImageReady included) have a "dither" option to remove this kind of banding.

Might just be worth checking that you're not accidentally changing the colour mode of your photograph when you edit it and in so-doing reducing the number of colours available.

John

Nikon AF-S Nikkor 18-55mm f/3.5-5.6G DX VR

08/01/2002 05:48:07 PM · #12

I was referring to the original jpegs (yes, I''m getting 6 on a floppy).
I cropped part of the image that I liked (by using the info window to arrive at an area of 640x480) and that made the sky more prominent. And also made the banding very noticeable and ugly (good for at least 12 comments!)Then I looked back at the original jpegs and it was there to begin with.

Perhaps, banding is not the correct term here. What I see on the sky is blotches in varying width of 2-4px that are darker and scattered over the sky. Perhaps my camera wanted to help me out by antique-ing the images for me :)

PS: do you think it would be helpful to clarify the submission rules somewhat? The rules mention whole image corrections but doesn''t say anything about, say, channels. For instance a technique used for unsharpen/despeckle is to unsharpen the green and red channels and to despeckle the blue channel. (I haven''t done anything by individual channel here). Even with the allowed curves you can lay an extreme curve that is definitely veering towards manipulation. A Photoshopper develops certain techniques that he/she perceives as normal MO but that may not be allowed for dp challenge submissions.

Edit: just read some new posts here. I used RGB in Photoshop. Yes, the dissatisfaction with the camera is growing but will need to live with it for a while longer.

BTW, if the "he" referred to in several posts is me, just wanted to say this he is a she. lol

* This message has been edited by the author on 8/1/2002 6:06:20 PM.

myqyl

Nikon D3100

08/01/2002 07:19:32 PM · #13

Ok, I'll ask the obvious but stupid question... What is banding? Could someone link to an example of it?

Thanks.

myqyl

Nikon D3100

Nikon AF-S Nikkor 18-55mm f/3.5-5.6G DX VR

08/01/2002 07:19:33 PM · #14

Double post monster strikes again...
Double post monster strikes again...

* This message has been edited by the author on 8/1/2002 7:19:32 PM.

sohr

Nikon Coolpix 990

08/01/2002 09:58:16 PM · #15

Banding is where you have visible blocks of color where there should be a smooth transition of colors. It could be caused by any number of things, but common is using too much compression, allowing too few colors (for instance, saving a photo as a 64-color GIF), or in some cases increasing tonal range too much.

Here is an example of an image that exhibits color banding. Note the sky and the water... you can almost see "curves" of blocks of a single color!

myqyl

Nikon D3100

Nikon AF-S Nikkor 18-55mm f/3.5-5.6G DX VR

08/01/2002 10:35:20 PM · #16

Thanks :)

08/01/2002 10:53:21 PM · #17

Sohr, yes that is banding and sorry, I used the wrong terminology. See my post above, what I see is blotches of darker pixels. Will post a little image of that blue sky the way it comes off the camera after I have some dinner.

welcher