Blue Sky Backgrounds

[IanL]

Hello,
First post and a novice. I've taken several shots of buildings with a Canon EOS (each photo 4mg / JPG) with very dark blue sky backgrounds. There are no clouds in the sky. I need to resize each photo down to approx 350kb for the Internet. I'm using Corel Paint Shop Pro X2. I've run various process's like smart photo fix, sharpen, then improved the saturation and then re sized at 75% "weighted average". When I view the photo on the Internet the blue sky seems to be in lines. Any tips on how I can stop this and get an even blue colour.

Thanks

[hartpaul]

Hi Ian L,
If it is on the internet , do you have a link to the image so we can see exactly what you mean. ie, do you nmean lines or bands of colour, acttual black lines.
Is it viewable on other computers / monitors . There are a number of possibilities depending on what you mean by lines?

You say 4 mg images. Do you mean 4 MB.
JUst reading your process , sharpening should be a final step after you have resized.

Are the lines visible on your image before uploading to internet?

A 4 MB image would be about 3000 pixels on the longest side. If you are reducing this to 75% then that will still be at least 2000 pixels. Some sites heavily compress images that are too large . TRy with an image that is 800 pixels on the longest side and see if the bands persist.

[IanL]

Hello, Here is one link. I have others of course as I'm building the site. http://www.churchhistories.net.au/avoca02.htm

[IanL]

Hello, Here is another example http://www.churchhistories.net.au/avoca01.htm Yes the original photos are 4MG in size and yes I can see the fault on other computer screens. It just seems to happen with all dark blue sky backgrounds. Any help would be much appreciated as I have hundreds to do.

[teknisyan]

When you resize the image via IMAGE > RESIZE, did you also change the value of RESOLUTION? You may want to keep the same resolution value as the original image even if you resized the image.

[df]

Rather than reduce the quality of the file you should reduce the size first. If your intention is to display these at the size that you've linked too, 430px × 290px, you shouldn't supply jpegs at 2,684px × 1,782px. I assume since you're trying to keep the file "size" low (storage space wise) that you've used the Wizard in the save dialog or something similar. I'd much rather resize the file before sharpening then saving that at a higher quality. Basically at 2000+ px wide you had to suffer greatly with your quality settings.

Do everything else to your file, resize, sharpen to taste (only if it needs it), then save at a high enough quality.

Edit:
I just reread your original post and you'll likely see an improvement if instead of resizing to 75% you resize to the actual final size you want to end up at, 430 x 290.

[Jean-Luc]

Ian,
could you post your original file somewhere so we can try to reduce it without the banding problem?
Or you may send the file directly to those who are willing to help : my email jeanluc.ernst[at]base.be
I think a have a solution but need to work with the original size.

Best regards,
Jean-Luc Ernst

[IanL]

Hi Everyone,
Thanks so much for all your valuable help. I'll work thru your ideas on the weekend and educated myself. I've uploaded one original file here http://www.churchhistories.net.au/test/20252.9.JPG for those who wanted to "play with it". Any step by step instructions I can follow will be gratefully received. BTW, I've upgraded to X4 yesterday.

Ian L

[LindaSue]

The problem is that you're compressing the JPGs too much. The photo looks just fine at 75% with a compression factor of 25 but as soon as I jump to 30, the bands start to appear. At 35 they look just like your example.

[df]

Great looking shots Ian. Nice composition.

I grabbed the shot you gave us. Straight off the web it's 3.8 mb (saved from PSP at full res. no compression).
I resized it to 75% in PSP and saved again and it only shrank to 3.38mb.
I then undid that and resized and cropped to 430x290, then saved that and I got 103kb, but there was no banding.


Not My Image1-s by cabbiinc, on Flickr

I would do most edits you wanted too to the image first, then resize, then sharpen for that size, then save. A typical workflow would be something like this:
Adjust brightness and contrast (if needed)
Adjust color balance (if needed)
Adjust noise (if needed)
Correct for lens distortion (if needed)
Adjust tilt (if needed)
Touch up blemishes, clone out anything that needed it, etc..
Save As for further updates.
Resize to final size
Sharpen to taste
Save with Compression set to 0.

[LindaSue]

I got the impression that IanL wants to post the photos at 75% of the original size, not just 430x290 pixels. I assumed that the smaller version was just serving as a "thumbnail" for the full-size version.

[RoseW]

If he is using the smaller image coded as 430 wide then he has to code his web page site to link to the full size image.....even then I don't think it has to be the original size. It could be a 900 or 1000 wide and result in as good a view.
I wondered why he wasn't using 'Smart Size' as the resizing method.
There are step resizers script that work well when there is one colour such as the sky (Sheilsoft resizing script reduces in steps until the final amount then offers a final sharpening)

Rose

[hartpaul]

Hi Iani,
Thanks for the practise on this image.
I loaded the image into the Edit space on PSP X4.
1. Used Crop Tool (5th from top) and set a size of 860 x 580 and ticked the Maintain Aspect Ratio box.
2. Using the handles I drew the box out til it included all of the church and was able to crop off shadow at bottom and at left hand side.
3. Image -->Resize Tick Resample using (Bicubic) , Lock Aspect Ratio, Sharpness left at Default.
Pixel Dimensions Type in 430 for the width and 290 for the height.

Since this is a web image forget all about the resolution , the number of pixels is the main concern.
(See http://digitaltoolz.blogspot.com.au/200 ... image.html )

4. Adjust --> Sharpness - Unsharp Mask Radius 1 , Strength 100 , Clipping 5

5. File -->Save As Change name, Save type Jpg Click Options and set Compression factor of 10. The final image is 56 Kb in size.

I got the impression that IanL wants to post the photos at 75% of the original size, not just 430x290 pixels. I assumed that the smaller version was just serving as a "thumbnail" for the full-size version.

The images that he gave links for did not link to larger images, but if so then Iani should also tell us the size of these final images as well. His "Thumbnails?" seem to have very faint banding in the sky so am guessing that is what he is referring to.

[df]

I got the impression that IanL wants to post the photos at 75% of the original size, not just 430x290 pixels. I assumed that the smaller version was just serving as a "thumbnail" for the full-size version.

If that's the case then you'll never get a quality image at that pixel count for that file size. There has to be some give somewhere.

[LindaSue]

I got the impression that IanL wants to post the photos at 75% of the original size, not just 430x290 pixels. I assumed that the smaller version was just serving as a "thumbnail" for the full-size version.

If that's the case then you'll never get a quality image at that pixel count for that file size. There has to be some give somewhere.

That's what I was thinking too but maybe he wants people to be able to download the full size versions of the photos if they choose. If that's the case then he should create a separate thumbnail and link to the full size images. In any case, the banding is there whether the photo is artificially shrunk down on his website or not. If he doesn't need them to be that large then he can easily avoid the banding by doing as you've suggested.