Artefacts using LR/Mogrify

[Slyvain]

Hello everyone

I've noticed artefacts (in corners, around objects, ...) on my resized pictures when I use LR/Mogrify to export my photos.
I don't have them if I export the image without resize/border/compression and proceed with Photoshop.

(see in attachment the difference ... corner top left of a picture)

Version of LR : 2.4
Version of plugin : 4.28

Here are my LR/Mogrify options :

Export JPEG : Quality 1''
Border : 1px
Resize to fit "Fit Inside" ... 7''x7'' px
Keep aspect Ratio checked
Fit any outer borders into this target size checked
Compress to Fit : 35' Kb
Basic sharpening : '.11

Any idea where it would come from ? Thanks for your help

Sylvain

 

[Brad Snyder]

Sylvain, try again with the attachments. I for one, can't see what you mean, they're too small, don't seem to be a correct image.

 

[Slyvain]

Hi Brad
Yes they're 2''% crop of the top left corner of the pictures to show the difference.
I uploaded the whole pictures here :
Picture with Lightroom
Picture with Photoshop

 

[Brad Snyder]

OK, now I see it, but no idea what's causing it.
So, one image is a straight export from Lr, and the other is Lr via LR/Mogrify?

Have you corresponded directly with the author Tim Armes? (Tim writes the Lr plugin interface, not the Image Magick software that does the actual pixel crunching). He does have a day job, but he's usually pretty responsive.

 

[sizzlingbadger]

I have seen similar issues and I believe it is because LR creates a jpg and then Mogrify adds the overlay image and creates another jpeg. This means your image is being compressed twice using the jpeg algorithm.

I could be wrong here but this is what I think causes the problem. I'm sure Tim would know better.

 

[Mark Sirota]

I agree with Nik. If you set both LR and Mogrify to Quality 1'', I bet it'll go away. Or have LR produce a TIFF, and have Mogrify convert it to a JPEG.

Also, are you having LR fit inside a 7''x7'' box, then asking Mogrify to downsize it to 698x698? Or are you having LR produce 698x698, and then having Mogrify add the border to the outside?

 

[Denis Pagé]

And compress to fit 35'Kb may defeat the Quality 1'' setting...

 

[Slyvain]

It is indeed the compression to 35' Kb that creates the artefacts :icon_neutral:
Without the checkbox checked, my image is 364 Kb and perfect !

I can then compress with Photoshop (which doesn't create artefacts btw), and my final image goes from 364 to 3'6 Kb (with maximal quality selected while "save as").

Problem solved ... kind of ... I'd like the Mogrify compression be less destructive :icon_neutral:

 

[Mark Sirota]

In that case, consider using Jeffrey Friedl's Metadata Wrangler to eliminate some of the metadata, rather than recompressing the JPEG. That's probably what your Photoshop "compression" is doing, if you've got it set to maximum quality.

 

[Slyvain]

Good idea, I'll take a look