Specific Editing 360 image reduces quality ~ what am I doing wrong?

[Paul Cooper]

I have a simple workflow for editing Samsung Gear 360 (2017) Images

Using CS3 (I know, but I bought this one stand alone and have not updated to suck-your-money-for-life yet)

Open JPG image
Adobe says

xnView says
not sure why the difference in print size, I think this might be what is causing the problem?

Image > Rotate Canvas > 180 degrees

Filter > Distort > Polar Coordinates > Rectangular to Polar > Go

Zoom in loads and find the tripod feet.



Use clone/patch/magic/luck to remove tripod remnants and just leave bricks

Filter > Distort > Polar Coordinates >Polar to Rectangular> Go

Image > Rotate Canvas > 180 degrees

Save as {new name} to highest quality JPG option

BUT

The file size is radically different and detail is lost (zoom in on the statue’s head).



What am I doing wrong, and is it time to bite the bullet and upgrade

0025 = original = 6.7Mb
0025-NoTP = modified = 2.2Mb

 

[thebestcpu]

Hi Paul
I did an examination of the two files in detail and the second with No TriPod was saved at a higher JPEG compression than the first. I believe that is the reason and will come back with more details in a bit. It is not related to the print size as the pixel dimensions are identical between the two.
John Wheeler

 

[thebestcpu]

HI Paul
Back with the details

There are many many factors in JPEG compression yet most often the most telling are the Luminance and Chromiance compression tables used on a given image. Using the JPEGsnoop program the two tables are shown below.

The first set of tables is for the original image (I assume straight from the camera. The lowest compression is when the table values are all set to 1 which is the case for the Image with Tripod Image:


COMPRESSION TABLES USED WITH TRIPOD IMAGE
—————————————————————————————————
----
Precision=8 bits
Destination ID=0 (Luminance)
DQT, Row #0: 1 1 1 1 1 1 1 1
DQT, Row #1: 1 1 1 1 1 1 1 1
DQT, Row #2: 1 1 1 1 1 1 1 1
DQT, Row #3: 1 1 1 1 1 1 1 1
DQT, Row #4: 1 1 1 1 1 1 1 1
DQT, Row #5: 1 1 1 1 1 1 1 1
DQT, Row #6: 1 1 1 1 1 1 1 1
DQT, Row #7: 1 1 1 1 1 1 1 1
Approx quality factor = 100.00 (scaling=2.99 variance=6.13)

*** Marker: DQT (xFFDB) ***
Define a Quantization Table.
OFFSET: 0x0000CAD8
Table length = 67
----
Precision=8 bits
Destination ID=1 (Chrominance)
DQT, Row #0: 1 1 1 1 1 1 1 1
DQT, Row #1: 1 1 1 1 1 1 1 1
DQT, Row #2: 1 1 1 1 1 1 1 1
DQT, Row #3: 1 1 1 1 1 1 1 1
DQT, Row #4: 1 1 1 1 1 1 1 1
DQT, Row #5: 1 1 1 1 1 1 1 1
DQT, Row #6: 1 1 1 1 1 1 1 1
DQT, Row #7: 1 1 1 1 1 1 1 1


**************************************************************************

However, when you resaved as a JPEG, the compression was at quality level 10 (not the max of 12) in Photoshop yet even at compression level 12, I don't think it is as good as the original image. Note that the tables have many higher numbers than "1" which reduces the file size at the expense of quality.
I suggest compression at Photoshop level 12 as a start for better quality:





COMPRESSION TABLES USED ON NO TRIPOD IMAGE
——————————————————————

Precision=8 bits
Destination ID=0 (Luminance)
DQT, Row #0: 2 2 3 4 5 6 8 11
DQT, Row #1: 2 2 2 4 5 7 9 11
DQT, Row #2: 3 2 3 5 7 9 11 12
DQT, Row #3: 4 4 5 7 9 11 12 12
DQT, Row #4: 5 5 7 9 11 12 12 12
DQT, Row #5: 6 7 9 11 12 12 12 12
DQT, Row #6: 8 9 11 12 12 12 12 12
DQT, Row #7: 11 11 12 12 12 12 12 12
Approx quality factor = 91.64 (scaling=16.71 variance=22.54)
----
Precision=8 bits
Destination ID=1 (Chrominance)
DQT, Row #0: 3 3 7 13 15 15 15 15
DQT, Row #1: 3 4 7 13 14 12 12 12
DQT, Row #2: 7 7 13 14 12 12 12 12
DQT, Row #3: 13 13 14 12 12 12 12 12
DQT, Row #4: 15 14 12 12 12 12 12 12
DQT, Row #5: 15 12 12 12 12 12 12 12
DQT, Row #6: 15 12 12 12 12 12 12 12
DQT, Row #7: 15 12 12 12 12 12 12 12
Approx quality factor = 92.57 (scaling=14.85 variance=23.00)


Hope this is of some help
John Wheeler

 

[Paul Cooper]

There we go John, back to the old "you don't know what you don't know".
To save the JPG I ticked the box [Maximum] which had a 'value' of 10. I assumed this was the maximum!
I hadn't realised you could then slide the number up to 12!
PS 'remembers' 12 now so at some time I must have set it to 10 for some reason and it has been degrading my photo's ever since.
Images now at 5.3 Mb so nearly as good as the original.

NB I know re-saving JPG's is not ideal, but I have no option.

Finally, there are these options. Which one saves the most detail (I am not too concerned about file size). At the moment it's progressive 3.

( ) Baseline (*Standard")
( ) Baseline Optimised
( ) Progressive
Scans: 3

Thanks for your reply ~ rarely do I receive as comprehensive an answer in any forum as that one.

 

[thebestcpu]

Hi Paul
This link probably covers the factors pretty well. If you need more details I could look at it:
https://forums.adobe.com/thread/1962929

 

[Paul Cooper]

That, and the embedded link, are all I needed to know. Thanks guys, really quick and informative answers

 

[thebestcpu]

Your welcome Paul