Jump to content

Recommended Posts

100 ISO

F 4

1/40

5760 x 3840

Max Quality JPEG - 12

 

Failed for Compression Artefacts/Soft or Lacking Definition

 

I0000K_mQ.cqxH5A.jpg

 

I0000Ehlq7B_QII0.jpg

 

I could have reduced the image size but not sure what I could do about compression artefacts as it was saved at Max Quality.

 

Should have increased ISO/faster shutter but a bit late for that now - I had just walked in from daylight and took the snap in tree shade.  I'm a bit surprised that it was called for focus though agree that it isn't pin sharp.

 

Any advice please. 

Edited by geogphotos
Link to post
Share on other sites
24 minutes ago, spacecadet said:

I assume the the top image is full frame- are you sure that's a 100% crop? If it is I can't see any faults.

 

It's a bit hard ( for me) getting exactly a 100% crop because Photoshelter serves up an image at a specified size. I'm open to suggestions about how to do it.

 

I0000uDLKysYwlPc.jpg

 

I did send in a request for feedback on this specific failure being the first of what turned out to be a recent crop of three fails ( at the moment!) , but the reply included two other QC fails so was generic in nature (one of which I posted on the forum a few days ago and was chroma noise in shadows that I had lifted - a fair cop guv). 

 

I could have submitted this whole lot as Reportage and bypassed QC but most of them were absolutely fine as normal Stock and I didn't actually give it a thought until this failed. 

 

I can't see that this image, whatever its faults, is soft or lacking definition. And so that leaves me feeling puzzled.

Edited by geogphotos
Link to post
Share on other sites

I can see the compression artefacts, just above the word trespassers in particular, but all around the text if you look closely enough. Did you fix your noise issue? I didn't see a reply from you in the thread where you were having noise issues in ISO 100 images.

Link to post
Share on other sites
7 minutes ago, Cal said:

I can see the compression artefacts, just above the word trespassers in particular, but all around the text if you look closely enough. Did you fix your noise issue? I didn't see a reply from you in the thread where you were having noise issues in ISO 100 images.

 

Thanks Cal. I fixed the noise issue by not lightening the dark shadows so much. 

 

So what can be done about compression artefacts?

Edited by geogphotos
Link to post
Share on other sites
4 minutes ago, geogphotos said:

 

Thanks Cal. I fixed the noise issue by not lightening the dark shadows so much. 

 

So what can be done about compression artefacts?

 

What's your process? I don't know what Photoshelter is but something in your process looks to be removing quality from your images. Although I almost always use my camera raw files and ignore the JPEGs, I do shoot in raw and JPEG and did a quick check of some of my unprocessed ones that have signs in. None of the SOOC JPEGs have the artefacts yours do, which is as I'd expect. Normally you see that when you've re-saved a JPEG at a lower quality setting, say 80% or lower is when it starts to become noticeable.

 

If you still can't see what I'm talking about, blow up that image you posted of just the red sign and look around the white text. You can see where the red stops being uniform and starts to take on a mushy/mottled appearance, and how the local contrast immediately around the white lettering is harsh. The process I use, which is to import the raw into LR/PS, process it, then export as 100% quality JPEG, doesn't produce this kind of artefacting, so you need to review your process to see what is causing it.

Link to post
Share on other sites

I have a hunch that it is something to do with white lettering on the colour red. 

 

I do exactly as you do RAW-Photoshop-Save Max JPEG ie) not compressed apart from RAW to JPEG 12 conversion

 

A related thought does cross my mind about what Alamy does to images because they compress them right down to only approx 2Mb from ones submitted at approx 10Mb so they must introduce compression artefacts. 

 

I can't see that my image is unduly soft. 

 

I've submitted this image as Reportage.

 

 

Edited by geogphotos
Link to post
Share on other sites

This is another image of the same sort:

 

My image is 5368 x 3840 (12.2MB compressed JPEG)

 

I0000WpZf_8dEWQc.jpg

 

I0000a4Wh49m1.So.jpg

 

This is how it looks on Alamy compressed to 1.2 Mb

 

I00002LVZ.uS7G0c.jpg

 

Contributor: geogphotos / Alamy Stock Photo 
Image ID: 2DA3PYH 
File size: 
59 MB (1.3 MB Compressed download)  
Dimensions: 5368 x 3840 px | 45.4 x 32.5 cm | 17.9 x 12.8 inches | 300dpi

 

 

Edited by geogphotos
Link to post
Share on other sites
21 minutes ago, geogphotos said:

I0000.MYNGerDY1U.jpg

 

Can't see any compression artefacts though the red is blotchy. that might just be minute noise patterns, which I'd think would be more than acceptable as they're not prominent and this is a high zoom.

 

 

6 minutes ago, geogphotos said:

This is another image of the same sort:

 

My image is 5368 x 3840 (12.2MB compressed JPEG)

 

I0000WpZf_8dEWQc.jpg

 

I0000a4Wh49m1.So.jpg

 

This is how it looks on Alamy compressed to 1.2 Mb

 

I00002LVZ.uS7G0c.jpg

 

Contributor: geogphotos / Alamy Stock Photo 
Image ID: 2DA3PYH 
File size: 
59 MB (1.3 MB Compressed download)  
Dimensions: 5368 x 3840 px | 45.4 x 32.5 cm | 17.9 x 12.8 inches | 300dpi

 

 

 

The alamy image definitely makes the compression artefacts worse but the top two in this quote do still show it to some degree. 

Link to post
Share on other sites
5 minutes ago, Cal said:

 

Can't see any compression artefacts though the red is blotchy. that might just be minute noise patterns, which I'd think would be more than acceptable as they're not prominent and this is a high zoom.

 

 

 

The alamy image definitely makes the compression artefacts worse but the top two in this quote do still show it to some degree. 

 

 

Alamy compressing it from 12.2 Mb to 1.3Mb is hardly going to help. 

 

Interesting that with my first image at 500% you can't detect compression artefacts. It does make me think that this is about white lettering/red background  ( possibly an optical effect) rather than compression artefacts. In any case there nothing I can do because the JPEGs are all at MAX size - I can't compress them any less.

Edited by geogphotos
Link to post
Share on other sites
1 minute ago, geogphotos said:

 

 

Compressing it from 12.2 Mb to 1.3Mb is hardly going to help. 

 

 

I doubt QC sees the massively compressed version in the preview otherwise it follows logically that no images would pass. Have often been tempted to have a friend buy one of my images as PU so I can compare the data to see if alamy does change the JPEG at all. My hope would be that apart from perhaps fiddling some of the EXIF data to say remove GPS info the JPEG content itself should be identical to what the contributor has uploaded from their computer.

 

BTW white lettering on red isn't going to cause JPEG artefacts. It must be something else in the process that is altering the image, or they are somehow being altered in between your computer and this page.

Link to post
Share on other sites
3 minutes ago, Cal said:

 

 

I doubt QC sees the massively compressed version in the preview otherwise it follows logically that no images would pass. Have often been tempted to have a friend buy one of my images as PU so I can compare the data to see if alamy does change the JPEG at all. My hope would be that apart from perhaps fiddling some of the EXIF data to say remove GPS info the JPEG content itself should be identical to what the contributor has uploaded from their computer.

 

BTW white lettering on red isn't going to cause JPEG artefacts. It must be something else in the process that is altering the image, or they are somehow being altered in between your computer and this page.

 

 

I'm struggling with Alamy's logic of assessing images for compression artefacts ( at 12.2Mb) and then deliberately creating them by compressing the original file (1.3Mb)!

 

What I am posting here are screenshots.

Edited by geogphotos
Link to post
Share on other sites
6 minutes ago, geogphotos said:

 

 

I'm struggling with Alamy's logic of assessing images for compression artefacts ( at 12.2Mb) and then deliberately creating them by compressing the original file (1.3Mb)!

 

What I am posting here are screenshots.

 

Have you asked Alamy? I know in the past when someone commented here on a QC fail alamy offered to provide a screenshot. Maybe you can compare what they see at their end to what you do at yours. It is entirely possible our for sale JPEGs are compressed a little and in certain circumstances like yours could create the problem. I'm just guessing at this point, best of luck in getting it resolved.

Link to post
Share on other sites
17 minutes ago, Mr Standfast said:

 

 

Maybe a bit of shake? Shot at 1/40th?

 

Always possible that there is more than one contributing factor of softness.

 

🤔

 

 

 

 

Yes I accept that - but that is a 500% crop to look at possible artefacts.

Edited by geogphotos
Link to post
Share on other sites
1 hour ago, geogphotos said:

 

Yes I accept that - but that is a 500% crop to look at possible artefacts.

By my reckoning it's far less than that.

In your full-frame image viewed on my 1200px wide monitor, the word "trespassers" is about 10mm. wide. On the crop you reckon as 500% it's about 125mm. wide.

Your 5760 px image should be 5760/1200 or 4.8x the width of my monitor. So the word should be about 10 x 4.8 or 48mm. wide and your "500%" is actually about 48/125 or about 38%. I agree with the suggestion of camera shake.

If my logic is correct, and if this is how you do your 100% assessment it may have let you down.

The other image is dead sharp at my end.

Link to post
Share on other sites
1 hour ago, spacecadet said:

By my reckoning it's far less than that.

In your full-frame image viewed on my 1200px wide monitor, the word "trespassers" is about 10mm. wide. On the crop you reckon as 500% it's about 125mm. wide.

Your 5760 px image should be 5760/1200 or 4.8x the width of my monitor. So the word should be about 10 x 4.8 or 48mm. wide and your "500%" is actually about 48/125 or about 38%. I agree with the suggestion of camera shake.

If my logic is correct, and if this is how you do your 100% assessment it may have let you down.

The other image is dead sharp at my end.

 

No it isn't the way I view 100%. It is a screenshot taken when the image was zoomed 500%.

 

But as I explained above in reply to you  that is messed up by Photoshelter serving up images at a set size.

 

I have accepted the focus issue and know how to fix that.

 

Just to recap:

 

I am not challenging the QC decision.

 

I am trying to understand about compression artefacts - how to understand and overcome the problem.  

 

 

Edited by geogphotos
Link to post
Share on other sites

Stuff like this:

 

There is actually no difference in the image compression of red as there is from other colours. It is actually an illusion because of how the human eye perceives colour information via our colour sensitive cones.

By population, about 64% of the cones in the human eye are red-sensitive. This means that we see red variations (artefacts) more clearly than other colours variation. Second to red is green at 32% and 2% of cones are blue sensitive.

So ........ the reason the red and blue look so different is because there is a big gap between the number of red cones in the human eye used to receive this colour information than blue cones.

Edited by geogphotos
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.