Image quality again

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hpbirkeland
Posts: 157
Joined: Fri Jul 01, 2016 9:32 pm

Image quality again

Post by hpbirkeland » Fri May 18, 2018 9:12 pm

Hi,
I feel I need to address the image quality on Clickasnap a bit, and I'll compare the quality on Clickasnap with the quality on 500px, one of the largest image sharing platforms.

I have taken two screenshots of one of my recent images, Solbergfoss Selfie, which you can see here. The first one is from Clickasnap, at the highest possible resolution. The second one is from 500px, at the same resolution. First of all look at the power lines. The Clickasnap version suffers from very bad aliasing and I find them disturbing to look at. In the 500px version, the power lines are very close to perfect. I have uploaded the exact same file to both sites, at full size, 5196x3462 pixels.

In this blog post, Tom says: "We actually compress images incredibly efficiently and generally speaking it is very difficult to determine that they have been compressed." No, In fact images are compressed way too much, and it is very easy to see. I have seen this on many of my images, and also on others' but this time it was so obvious that I could not let it pass.

Also, I have tried to adjust the TrueForm settings. This, as far as I have understood it, should ensure that quality was kept at a maximum. Well, as I adjust the settings, which look very much like an Unsharp Mask feature (nothing fancy about that) I can see the effect in the preview, but it is not possible to get rid of the aliasing. Also this does nothing to the final image. Clicking the "View" button that appears when hovering the mouse over the preview both before and after the "Apply Changes" button makes no difference at all. Nor after reloading the image page. And why should it? I see no point in adjusting a small thumbnail and guessing how the result will look on the full size image. The preview should be a 100% crop of the image, not a small thumbnail.

In the same blog post as above, Tom also says: "This new image filter technology is called ‘TrueForm‘ and ensures your photos are always seen exactly as you intended." Again a big NO! I never intended those power lines to look like strings of dots and short lines floating in the air by them selves. I intended them to look like they do on 500px.

I remember there was much talk about this last year around the time TrueForm was implemented and also before that, but lately it has been rather quiet. But the fact is that there is still a long way to go with the by far most important aspect of this site. I mean, even Facebook does this better!
Attachments
500px-quality.jpeg
Quality on 500px
500px-quality.jpeg (77.32 KiB) Viewed 975 times

hpbirkeland
Posts: 157
Joined: Fri Jul 01, 2016 9:32 pm

Re: Image quality again

Post by hpbirkeland » Fri May 18, 2018 9:14 pm

I had two attachments on this, but one didn't make it through for some reason. Here it is.
Attachments
CAS-quality.jpeg
Quality on Clickasnap
CAS-quality.jpeg (86.94 KiB) Viewed 974 times

tomoswald
Posts: 4017
Joined: Mon Jun 06, 2016 7:13 pm

Re: Image quality again

Post by tomoswald » Fri May 18, 2018 9:31 pm

Trueform isn’t used on main image pages anymore, it’s only used on thumbnails.

I will discuss image compression once our next stint is complete, however reducing the compression increases the bandwidth and storage costs and will reduce the payments per view as there is no net revenue increase. If the general consensus of the platform users is to do this then we will

tomoswald
Posts: 4017
Joined: Mon Jun 06, 2016 7:13 pm

Re: Image quality again

Post by tomoswald » Fri May 18, 2018 9:48 pm

Here is a comparison between ClickASnap and 500px, the difference is marginal at best. Both cables are aliased, a slight adjustment to our algorithm may correct this and bring it on par with 500px

Image

hpbirkeland
Posts: 157
Joined: Fri Jul 01, 2016 9:32 pm

Re: Image quality again

Post by hpbirkeland » Fri May 18, 2018 10:30 pm

I understand your concern about cost, but I don't really buy it. And that's because this reduction in quality doesn't really look like compression artifacts either. It has always looked to me as bad down-scaling, but I have never seen that mentioned here. And I did a test just now. I took my full size jpg into GIMP (don't have PS) and exported with heavy compression (20% quality) and no resize. File size is 464.6 kB. A crop of this file is attached here. As you can see, the sky is completely destroyed by the compression, but the power lines are still more or less fine.

I then scaled down the original to 1000x666 pixels the quick and dirty way with no interpolation and exported with a jpg quality of 90%. Not surprisingly, the result was pretty much identical to the image on Clickasnap! File size 199,0 kB.

So what remained now was to scale down to 1000x666 once more, but this time with Cubic interpolation and again with 90% jpg quality. File size was 166,4 kB. This is the smallest file of those three, and also the one with the best quality.

Therefore my theory is that compression is not the issue at all. It has everything to do with resizing. And you actually waste bandwith by downscaling the images without interpolation and therefore end up sending out larger files than you need and with lower quality. Turn on a high quality interpolation when you downsize the images and you get a Kinderegg: 1-you save bandwith, 2-higher quality images are displayed and 3-you get happier users.

Since it seems like I can't have more than one attachment in a post I'll attach the two remaining examples in comments. Please do not reply until you have seen them.
Attachments
Solbergfoss_0013_compress_20_crop.jpg
Crop of full size exported at 20%
Solbergfoss_0013_compress_20_crop.jpg (63.57 KiB) Viewed 964 times

hpbirkeland
Posts: 157
Joined: Fri Jul 01, 2016 9:32 pm

Re: Image quality again

Post by hpbirkeland » Fri May 18, 2018 10:32 pm

Here is the downscaled version without interpolation, identical to Clickasnap.
Attachments
Solbergfoss_0013_scale_1000_no_ip.jpg
Solbergfoss_0013_scale_1000_no_ip.jpg (194.3 KiB) Viewed 964 times
Last edited by hpbirkeland on Fri May 18, 2018 10:51 pm, edited 1 time in total.

hpbirkeland
Posts: 157
Joined: Fri Jul 01, 2016 9:32 pm

Re: Image quality again

Post by hpbirkeland » Fri May 18, 2018 10:35 pm

And here is the downscaled version with cubic interpolation, like it should be.
Attachments
Solbergfoss_0013_scale_1000_cubic.jpg
Solbergfoss_0013_scale_1000_cubic.jpg (162.51 KiB) Viewed 963 times

hpbirkeland
Posts: 157
Joined: Fri Jul 01, 2016 9:32 pm

Re: Image quality again

Post by hpbirkeland » Fri May 18, 2018 10:37 pm

Deleted
Last edited by hpbirkeland on Fri May 18, 2018 10:52 pm, edited 1 time in total.

hpbirkeland
Posts: 157
Joined: Fri Jul 01, 2016 9:32 pm

Re: Image quality again

Post by hpbirkeland » Fri May 18, 2018 10:40 pm

tomoswald wrote:
Fri May 18, 2018 9:48 pm
Here is a comparison between ClickASnap and 500px, the difference is marginal at best. Both cables are aliased, a slight adjustment to our algorithm may correct this and bring it on par with 500px

Image
The one from 500px is scaled down some, so they can't really be compared. The difference in my examples above are much bigger.

lauracaptain
Posts: 94
Joined: Wed May 17, 2017 5:51 pm

Re: Image quality again

Post by lauracaptain » Fri May 18, 2018 10:51 pm

Regarding your original post, I followed both links to your online photos and the full size image at 500px looks the best, you're right. I see what you are saying about the power lines. The image thumbnails on both sites have spotty powerlines, a little more so on ClickASnap. The image on ClickASnap does look better when you see it full size but the power lines aren't quite as smooth as on 500px.

I have had some trouble with this too.

Laura

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