Banding of the Sky???

[karlo reyes]

hi I'm just concerned with this observation. At first i thought its just my screen but a few friends already said that there's banding visible in the sky!!! Can you see it? This image was processed using Ps cs4 and i didn't see any banding at all but after uploading it at flickr its already visible. Why is this the only set that exhibits banding? As far as the other images I've uploaded are concerned they don't have this problem at all. thanks guys!

small image visible banding

large image also visible

 

[Michael Fontana]

karlo

yep - it's visible with ease - try some higher quality-settings when saving for web, as it shouldn't be in the tiffs - right?

 

[karlo reyes]

karlo

yep - it's visible with ease - try some higher quality-settings when saving for web, as it shouldn't be in the tiffs - right?

hi michael! higher around 6-7 quality (pscs4 options) jpg? that would be around 1.5mb - 2mb. tiff format for the web? im always saving it as jpg and i didn't have a problem before its this set alone..

 

[nicolas claris]

hi michael! higher around 6-7 quality (pscs4 options) jpg? that would be around 1.5mb - 2mb. tiff format for the web? im always saving it as jpg and i didn't have a problem before its this set alone..

Hi Karlo

Your image is showing banding here to…
The file is 392 Kb, so you should be wise to listen to the good advice of Michael!
Never save a JPEG under 8 with CS !
Banding in the sky happens quite often when compressing too much, there's quite a large gradient!

 

[karlo reyes]

Hi Karlo

Your image is showing banding here to…
The file is 392 Kb, so you should be wise to listen to the good advice of Michael!
Never save a JPEG under 8 with CS !
Banding in the sky happens quite often when compressing too much, there's quite a large gradient!

got it! thanks nicolas!

 

[Asher Kelman]

Explain to me the banding we are talking about. I see an arc of layering in the sky which could be an artifact or else could be unusual layering of cloud cover.

Horizontal banding occurs with even good sensors on clear blue skies and aluminum metal surfaces where slight changes in luminosity or color shift give rise to junctions like this.

I'd like to see an image that's prepared at 10 or 11.

Asher

 

[nicolas claris]

You're right Asher
this is not banding but jpeg compression artifacts…

 

[karlo reyes]

hi asher,

as per my discussion with another photog banding is the term he used regarding the layers visible in the sky. Its not only evident on this photo but to this photo aswell. see attached photo below.

i saved another image from raw then exported to maximum quality jpg 12 and size this time is at 6.81mb before uploading at flickr.

small version

big version

true enough the layering is gone. practical issues im thinking now is that do i have to save jpg at 6mb up always? it eats a lot of space not to mention slows up my connection when multiple images are being opened. thank you very much guys!

much respect,
karlo

 

[nicolas claris]

Hi Karlo
If you want your image to keep quality (good) you should avoid flickr.
They have strong compression (your image prove it).
You better save your image at say 800 pix (larger side) at the compression rate of 8 in CS and have your image hosted in a place that don't compress your file.
Loss of time (uploading 8mb files), loss of quality… hmmm

Maybe some other OPFers have a better experience with flickr?

 

[Michael Fontana]

I agree, Nicolas

while not using Flickr, I' ve been wondering about the image weight of the originally posted image - about 392 kb (!!) and its quality.

But now, it's clear that these artefacts are due to the double jpg compression:
the first when creating the webjpg in Photoshop, then Flickr opens it and does another jpg-compression, which leads to the heavy image and these artefacts.

Karlo, you can test this by reopening your original image in PS and resaving it - exactly that (or worse) happend. How comes your image is at 240 dpi? Try to bring it to 72 prior to send it to Flickr.

Usually a image in that size should show no artefacts with about 80 - 200 kb of weight... but not 392...

I find it pretty dull to have 7 MB of upload for showing a 1024 pix-image...

 

[StuartRae]

Hi Carlos.

a image in that size should show no artefacts with about 80 - 200 kb

To prove Michael's point, here's your file re-compressed to 87Kb using Xat Image Optimiser at 70% quality. No banding.

BTW, I don't see how the dpi setting can have any effect on the way the image is displayed on screen.

Regards,

Stuart

 

[Michael Fontana]

.............
BTW, I don't see how the dpi setting can have any effect on the way the image is displayed on screen.
Regards,
Stuart

Stuart - I wrote that as I'm simply not aware how Flickr handles it.

BTW: The image weight depends much on the image as well, images with much details and a lot of diffrent tones and colors - like landscapes - are quite heavy, while °uniform° images can be quite light, whithout losses in quality.

 

[karlo reyes]

thanks guys for taking time, this discussion is really great! I'll try again to save the settings indicated below.. just one question I'm confused with this normally i don't mind the dpi.. where can i exactly adjust this setting?

Karlo, you can test this by reopening your original image in PS and resaving it - exactly that (or worse) happend. How comes your image is at 240 dpi? Try to bring it to 72 prior to send it to Flickr.

Usually a image in that size should show no artefacts with about 80 - 200 kb of weight... but not 392...

 

[Bart_van_der_Wolf]

... just one question I'm confused with this normally i don't mind the dpi.. where can i exactly adjust this setting?

The PPI tag setting should not influence the actual image data in the file, unless the tag is somehow incorrectly used in the downsampling algorithms. It's just a suggestion for the output dimensions in inches or metric units. Most modern displays/monitors have approximately a fixed 96 PPI setting, so the image size is only determined by the number of pixels.

In Photoshop, under the Image menu, Image size... . When you only want to adjust the PPI value, first uncheck the "Resample image:" box. By unchecking it, you only change the PPI tag of the file, the actual file size in pixels will remain unchanged.

BTW, Dots Per Inch (DPI) and Pixels Per Inch (PPI) are stricktly speaking 2 different things. PPI is related to the file/input dimensions, whereas DPI is related to the output technology (e.g. some inkjet printers can sub-divide each pixel in upto 16 dots per linear dimension, to simulate intermediate ink colors). Since different output technology can use different DPIs, with the same PPI input, DPI is a confusing metric unless the output technology is know beforehand.

Bart