Smugmug resizing introduces artifacts

mbridge87

Hello,

I think I have found a solution to this but wanted to hear what others thought and whether anyone else has experienced the issue.

Firstly does anyone know if Smugmug has altered its display algorithm in recent months? This would partially account for the problem, and massive headache, that I have experienced.

Please bare with me, this is quite long.

I'm still designing my site and the problem started when I decided to re-upload and optimize all of the images; I started with the landing page. Images on the landing page have a drop shadow and dimensions of 1024 x 640 before being increased by canvas size (in PS) to 1036 x 652 to account for the added drop shadow.

The increased document (1036 x 652) displayed horrible banding issues in the sky which two days of scratching my head could not resolve. There were many contradicting factors that pointed to either my set up or Smugmug, however, the overriding indicator was that the issue only presented itself on Smugmug, not on other sites such as Flickr. Finally today I realised that the reason this issue occurs is to do with Smugmug resizing the image.

By increasing the canvas size of my landing page image to 1036 x 652 I took it above the XL display size and hence it was resized by Smugmug. By ensuring that the final output, after the canvas size increase, was precisely 1024 px on the long edge meaning that no resizing occurred totally got rid of the issue. I applied the same method to other images within my galleries that had also been displaying this problem and they too were fixed. The gallery images had to be increased in size to 1280px, top end of the X2 size, which then resolved this problem.

Thankfully I can now use this workaround for the moment but I am still concerned about this for the future and hence would love to hear what others think. I also thought this was well worth writing just in case someone else is having the same problem.
If you would like to see the problem this link will take you to my landing page where I have left two images; one fixed and one with the issue. It’s worth noting that not all screens showed the problem as clearly as others, but on my Dell u2410 it was clear to me.
http://www.maxbridge.co.uk/

I'm so sorry this is so long but as you may have been able to tell this has been a source of some frustration over the last few days and there is a lot to explain.

Thanks guys.

thenickdude

For me on a Retina display, both images are shown at their "O" (Original) size, which means that SmugMug hasn't applied any scaling at all to the image files, they're your original uploaded JPEGs. The only scaling being applied is being applied by my web browser, where it scales down the image to fit the 960x605 slideshow size.

If I switch to a regular resolution display, both of the images are SmugMug's XL (scaled down) versions. These images are scaled down, sharpened according to your SmugMug settings, and are recompressed as JPEG, so there is always some quality loss involved in the process. That being said, I can't see any banding on my display.

Performing such a small resize is pretty much the worst case for scaling, since you're effectively taking something that already has its JPEG compression tuned to look good at about this size, smearing detail a little bit by scaling, and then incurring compression loss as the file is recompressed. If you were to upload oversized originals (like 4,000 pixel original-size images from your camera) the quality gain by collapsing all those extra pixels together (and all those JPEG artifacts from the original) into the smaller image should start off the sharpen/compress cycle with a much higher quality image. That should produce a better result.

EDIT: Also, if all else fails, you can reduce banding in smooth gradients by adding noise. Maybe you can use Lightroom/Photoshop's noise filter to add a tiny bit of noise to the image.

Bea

Hi Max,

Thanks for the detailed explanation. I see that you also emailed us - we'll respond to that email! Please allow us 24-48 hours to get back to you. Thanks for your patience:)

mbridge87

Hi,

Thanks for your reply,

I did try uploading the full quality file but the whole point was to reduce the file sizes to decrease load time.

I have also tested this on lots of different displays and did find that the issue was almost non existant on a macbook pro, it was extremely extremely subtle, but far more obvious on my larger Dell monitor and also present on my dell laptop (the inspiron 7000). If I take a screen capture of both images displayed on Smugmug and then apply a solar curve in PS the difference is very obvious. I would of course expect to see a difference here but not to the extent shown. I've uploaded an example of this to flickr which you can find here:

https://www.flickr.com/photos/90751009@N04/14425166337/

I've never had issues like this before and hence do not pretend to be any kind of an expert with this but I could definitely see a significant differnece between the two, and a big difference between the same file uploaded on both Smugmug and Flickr.

Hopefully the image above will help.

Thanks again.

mbridge87

Sorry wrote that before seeing your reply Vakvarju. I just thought I'd start this here to get other opinions and to share my experience in case anyone else comes across the same thing. Smugmug have been nothing but helpful with this I just thought it was worth posting here as well

thenickdude

Uploading larger images won't change the load time, as people will just be getting the SmugMug scaled-down version, not your uploaded original.

mbridge87

Wow. I had no idea about that! Seems obvious now you say it and totally solves the problem.

So. If I've understood you correctly. The reason for the artifacts I have been seeing is because the images have been resized by a very small amount. This also makes total sense I'd just never thought of it!

If I am simply uploading full size files should I do this at 100% (quality) in LR / PS or is it still a good idea to take it down a little, i.e. 75%? Is it also not necessary to sharpen the images at all then given that Smugmug apply their own sharpening? I've been following what I thought were best practices for images online, reducing size and sharpening etc., but it appears as though Smugmug is different. That's if I've understood this correctly.

Thanks again for the help.

Allen

The sharping you apply before upload is on the originals that will be used for printing. Smug only applies their
sharping on the generated display (down-sized) photos. They do not touch your originals.

thenickdude

Resizing by a small amount is bad in this situation, but it's also possible that SmugMug's JPEG compression is just a little bit too aggressive for your situation, meaning that it'll always end up saving filesize by posterising the sky, no matter how much or how little the image is resized. You'll need to give it a try to find out.

JPEG saves filesize by eliminating details it thinks won't be visible in the final image. This usually works pretty well, so it's odd that some of your monitors show up those differences.

Will your landing page image be a slideshow in your final version? If it's just going to be one static image, you could use a Single Image content block to display it, and set the size of the photo in the settings of that content block to Original. That'll always use your original JPEG instead of a SmugMug-resized version (which you can make about the right size in Photoshop, and save at a high quality setting to reduce posterisation).

mbridge87

Hey guys,

Thanks for your replies,

In terms of the sharpening Allen thank you for your response, which is certainly useful to know, but my apologies I do not think I was clear enough with my question. Throughout my research of the best workflow for online photo upload I have discovered that that the general consensus is for a few extra steps to be taken for your images to appear correctly online. One of which being an extra layer of sharpening, I forget why (obviously some sharpening is lost somehow), but the point was can I forgo this step as Smugmug actually apply their own sharpening, which I assume is precisely for this reason that, for the moment at least, slips my mind?

TheNIckDude – Again thank you very much for your reply. The landing page is going to be a slideshow of a number of images I’ve just taken the rest out for the moment while I fix this problem. Thankfully though I have tested the slideshow using the method I originally described and this has resolved the posterization / banding issue that I originally referred to. Sorry if I’ve been referring to the artefact incorrectly. No matter how many times I look this stuff up it never sinks in.

Given the above, the questions I was hoping you guys could answer are:


1) Do I need to use that generally accepted extra layer of sharpening (for uploading images online) or can I forgo this as Smugmug do this themselves?

2) If I can forgo this what are the optimal sharpening settings for Smugmug ?

3) Given that I will now upload original size files should I leave the quality setting at 100% on LR / PS or is it ok to reduce this down to say 75% for example? Will this help with load times?



Sorry I thought it was easier to summarize my ramblings; being succinct has never been a strong point of mine.

Thanks guys

mbridge87

bump