JPEG output quality versus EXIF

[DoctorBe]

In the Affinity Photo
Export routine I set the jpeg quality to 100%. However, when I read the EXIF of the exported file it says jpeg quality 80%. Can someone please explain this to me and suggest how I can truly export at 100%?

[walt.farrell]

Welcome to the Serif Affinity forums.

What kind of file did you start with?

As far as I know, there is no standard way to determine the quality setting that was used for JPG creation, so if you started with a file from some other application perhaps you're just seeing some residual EXIF info that application provided?

[DoctorBe]

47 minutes ago, walt.farrell said:

Welcome to the Serif Affinity forums.

What kind of file did you start with?

As far as I know, there is no standard way to determine the quality setting that was used for JPG creation, so if you started with a file from some other application perhaps you're just seeing some residual EXIF info that application provided?

My starting file was directly from Nikon D500 camera with jpeg quality set to the highest level.

[thomaso]

2 hours ago, DoctorBe said:

when I read the EXIF of the exported file it says jpeg quality 80%.

What software do you use to get the compression quality displayed? (APhoto and the ExifTool apparently do not)

[Hangman]

Hi @DoctorBe,

ExifTool correlates with the JPEG Quality Settings in Affinity Photo...

Exiftool -JPEGQualityEstimate filename.jpg

Processed RAW file exported as JPEG from Affinity Photo using Quality Settings of 100, 80 and 50

[walt.farrell]

11 hours ago, DoctorBe said:

My starting file was directly from Nikon D500 camera with jpeg quality set to the highest level.

Can you supply the file from the camera so we can look at it?

[Hangman]

This is what Nikon say on their website...

Quote

"Every time you capture an image on the camera’s sensor you record digital data. A JPEG file compresses that data and some basic editing is automatically done in the camera."

And what I see in my D750 manual...

So my assumption would be, as @walt.farrell is suggesting, that there is already a 'Level' of compression applied which differs depending on the camera settings but I don't know if that is the equivalent of the Quality setting in Affinity Photo editing and as such is recorded in the EXIF data in the same way.

A simple test would be to run the out-of-camera JPEG through ExifTool and then open the same file in Affinity Photo, export it as a JPEG with the Quality Slider set to 100% and run that through ExifTool as well to compare the results.

[thomaso]

12 hours ago, DoctorBe said:

how I can truly export at 100%?

Just in case: Do you notice a different file size in two exports with 80 vs. 100%? If not: If you set the quality value numerically, make sure you press the Tab or Enter key before clicking the "Export" button. Otherwise, a previously set value indicated by the slider position may be used for the export instead.

[DoctorBe]

11 hours ago, walt.farrell said:

Can you supply the file from the camera so we can look at it?

 

[DoctorBe]

Just now, DoctorBe said:

 

 

1 minute ago, DoctorBe said:

 

Sorry. It's the file with the bee 

[- S -]

3 hours ago, DoctorBe said:

Sorry. It's the file with the bee 

Although the below tag is in the file, I have never seen this tag added by Affinity Photo.

[File]       Comment           : CREATOR: gd-jpeg v1.0 (using IJG JPEG v62), quality = 85.

 

I don't see that tag in D500 out-of-camera JPG images either, usually just the below tag.

[Nikon]      JPGCompression    : Optimal Quality

Therefore, I suspect this tag is being added by some other software prior to being processed with Affinity Photo.  The image dimensions of your file are 3633×3051, rather than the standard 5568×3712, 4176x2784 or 2784x1856.  Has the image been resized in other software and this software is possibly adding the tag?

I would double-check with a new out-of-camera JPG straight out of the camera – without any other software used – that this tag is definitely not there before using Affinity Photo, but is added by Affinity Photo.

 

[Hangman]

Hi @DoctorBe,

Just to add to what @- S - has already mentioned above... it looks as though the file has been processed using the PHP GD Library and it has clearly been cropped since the ratio of the Bee image is 2.382:2 rather than the expected 3:2.

The vast majority of the EXIF data has been stripped from the file...

Taking an optimal-quality JPEG directly from the D500 I would expect the EXIF data to look more like the version on the right

Actual EXIF Data Left | Expected EXIF Data Right

[DoctorBe]

10 hours ago, - S - said:

Although the below tag is in the file, I have never seen this tag added by Affinity Photo.

[File]       Comment           : CREATOR: gd-jpeg v1.0 (using IJG JPEG v62), quality = 85.

 

I don't see that tag in D500 out-of-camera JPG images either, usually just the below tag.

[Nikon]      JPGCompression    : Optimal Quality

Therefore, I suspect this tag is being added by some other software prior to being processed with Affinity Photo.  The image dimensions of your file are 3633×3051, rather than the standard 5568×3712, 4176x2784 or 2784x1856.  Has the image been resized in other software and this software is possibly adding the tag?

I would double-check with a new out-of-camera JPG straight out of the camera – without any other software used – that this tag is definitely not there before using Affinity Photo, but is added by Affinity Photo.

 

The file goes directly into Affinity from the cameras XQD drive. Then it is cropped. Afterward, when I sent to the Nikonians site their EXIF says it was 80% JPEG Quality. Nikonian members ask why I reduce quality and I tell tehm I don't purposely do that. Those members largely use PS and other non-Affinty software and claim that their files are never reduced when uploaded to Nikonians. It's a little frustrating.

[DoctorBe]

4 hours ago, Hangman said:

Hi @DoctorBe,

Just to add to what @- S - has already mentioned above... it looks as though the file has been processed using the PHP GD Library and it has clearly been cropped since the ratio of the Bee image is 2.382:2 rather than the expected 3:2.

The vast majority of the EXIF data has been stripped from the file...

Taking an optimal-quality JPEG directly from the D500 I would expect the EXIF data to look more like the version on the right

Actual EXIF Data Left | Expected EXIF Data Right

I uploaded 3 files to NIKONIANS photosite: direct from XQD drive, via AFFINITY uncropped, via AFFINITY cropped. All 3 showed 80% jpeg quality when EXIF files generated by NIKONIANS were examined. So not Affinity at fault, but this makes me more confused than ever since camera is set to high/fine JPEG quality. Thanks for your help everyone.

[Hangman]

Hi @DoctorBe,

I've just taken a quick random look at some other images uploaded to the NIKONIANS photosite and of the ones I reviewed none include...

Quote

[File]       Comment           : CREATOR: gd-jpeg v1.0 (using IJG JPEG v62), quality = 85.

So I'm slightly unsure where or at what stage this is being added to the EXIF data for your file.

Would you be happy to ZIP one of the straight-out-of-camera JPEG files up and upload it to the forum without it touching Affinity Photo just so we can take a look at the EXIF Data straight out of the camera for comparison?

[DoctorBe]

4 hours ago, Hangman said:

Hi @DoctorBe,

I've just taken a quick random look at some other images uploaded to the NIKONIANS photosite and of the ones I reviewed none include...

So I'm slightly unsure where or at what stage this is being added to the EXIF data for your file.

Would you be happy to ZIP one of the straight-out-of-camera JPEG files up and upload it to the forum without it touching Affinity Photo just so we can take a look at the EXIF Data straight out of the camera for comparison?

This is directly from the XQD drive in the camera. thanks again.

[Old Bruce]

3 minutes ago, DoctorBe said:

This is directly from the XQD drive in the camera. thanks again.

The forum software may strip out the data when you upload a JPEG. What @Hangman asked for is a zipped file from your computer, not just the JPEG. Compress the file and post the zipped file.

 

[DoctorBe]

12 minutes ago, Old Bruce said:

The forum software may strip out the data when you upload a JPEG. What @Hangman asked for is a zipped file from your computer, not just the JPEG. Compress the file and post the zipped file.

 

Done. Thanks.

DSC_8938.JPG.zip

[Hangman]

Hi @DoctorBe,

Many thanks for the zipped file, it proves the relevant point which is that uploading images to the forum is the reason for the image compression and for stripping out the majority of the EXIF data...

When I look at your unzipped out-of-camera image downloading the source file by extracting it from the HTML source it shows a quality setting of 85, whereas your zipped file shows a quality setting of 100...

...together with the full complement of EXIF data... and it would appear that uploading to the forum is adding the PHP GD Library comment to the EXIF data since it doesn't appear in your zipped file but it does in your unzipped file.

-MacBook-Pro-2 JPEG Quality Settings % exiftool DSC_8938.JPG
ExifTool Version Number         : 12.32
File Name                       : DSC_8938.JPG
Directory                       : .
File Size                       : 13 MiB
File Modification Date/Time     : 2023:09:30 20:21:12+01:00
File Access Date/Time           : 2023:10:02 21:15:58+01:00
File Inode Change Date/Time     : 2023:10:02 21:15:56+01:00
File Permissions                : -rwxrwxrwx
File Type                       : JPEG
File Type Extension             : jpg
MIME Type                       : image/jpeg
Exif Byte Order                 : Little-endian (Intel, II)
Make                            : NIKON CORPORATION
Camera Model Name               : NIKON D500
Orientation                     : Horizontal (normal)
X Resolution                    : 300
Y Resolution                    : 300
Resolution Unit                 : inches
Software                        : Ver.1.20
Modify Date                     : 2023:09:30 15:21:12
Artist                          : 
Y Cb Cr Positioning             : Co-sited
Copyright                       : 
Exposure Time                   : 1/250
F Number                        : 7.1
Exposure Program                : Manual
ISO                             : 900
Sensitivity Type                : Recommended Exposure Index
Exif Version                    : 0230
Date/Time Original              : 2023:09:30 15:21:12
Create Date                     : 2023:09:30 15:21:12
Components Configuration        : Y, Cb, Cr, -
Compressed Bits Per Pixel       : 4
Exposure Compensation           : +1/3
Max Aperture Value              : 3.2
Metering Mode                   : Center-weighted average
Light Source                    : Cloudy
Flash                           : No Flash
Focal Length                    : 105.0 mm
Maker Note Version              : 2.11
Quality                         : Fine
White Balance                   : Cloudy
Focus Mode                      : Manual
Flash Setting                   : Normal
Flash Type                      : 
White Balance Fine Tune         : 0 0
WB RB Levels                    : 2.452636719 1.384765625 1 1
Program Shift                   : 0
Exposure Difference             : 0
Image Boundary                  : 0 0 5568 3712
External Flash Exposure Comp    : 0
Flash Exposure Bracket Value    : 0.0
Exposure Bracket Value          : 0
Crop Hi Speed                   : DX Uncropped (5600x3728 cropped to 5600x3728 at pixel 0,0)
Exposure Tuning                 : 0
Serial Number                   : 3031422
VR Info Version                 : 0100
Vibration Reduction             : Off
VR Mode                         : Normal
Active D-Lighting               : Normal
Picture Control Version         : 0200
Picture Control Name            : Standard
Picture Control Base            : Standard
Picture Control Adjust          : Default Settings
Picture Control Quick Adjust    : Normal
Clarity                         : 1.00
Brightness                      : Normal
Hue                             : None
Filter Effect                   : n/a
Toning Effect                   : n/a
Toning Saturation               : n/a
Time Zone                       : -05:00
Daylight Savings                : No
Date Display Format             : M/D/Y
ISO Expansion                   : Off
ISO2                            : 100
ISO Expansion 2                 : Off
Vignette Control                : Normal
Auto Distortion Control         : Off
HDR Info Version                : 0100
HDR                             : Off
HDR Level                       : Auto
HDR Smoothing                   : Off
HDR Level 2                     : n/a
Image Size RAW                  : Large
Lens Type                       : D
Lens                            : 105mm f/2.8
Flash Mode                      : Did Not Fire
Shooting Mode                   : Single-Frame, Auto ISO
Shot Info Version               : 0239
Firmware Version                : 1.20d
Rotation                        : Horizontal
Flicker Reduction Indicator     : On
JPG Compression                 : Optimal Quality
AE Bracketing Steps             : AE Bracketing Disabled
WB Bracketing Steps             : WB Bracketing Disabled
ADL Bracketing Step             : Normal
ADL Bracketing Type             : Off
Photo Shooting Menu Bank        : A
Primary Slot                    : XQD Card
ISO Auto Shutter Time           : 1/500 s
ISO Auto Hi Limit               : ISO 51200
Flicker Reduction               : Enable
Photo Shooting Menu Bank Image Area: DX (24x16)
Custom Settings Bank            : A
AF-C Priority Selection         : Release
AF-S Priority Selection         : Release
Number Of Focus Points          : 15 Points
Three-D Tracking Face Detection : Off
Block Shot AF Response          : 3
Focus Point Wrap                : No Wrap
AF Point Brightness             : Auto
ISO Display                     : Show ISO Sensitivity
Grid Display                    : Off
LCD Illumination                : Off
Electronic Front-Curtain Shutter: Off
Reverse Indicators              : - 0 +
Command Dials Reverse Rotation  : No
Easy Exposure Compensation      : Off
Exposure Control Step Size      : 1/3 EV
ISO Step Size                   : 1/3 EV
Exposure Comp Step Size         : 1/3 EV
Center Weighted Area Size       : 8 mm
Fine Tune Opt Matrix Metering   : 0
Fine Tune Opt Center Weighted   : 0
Fine Tune Opt Spot Metering     : 0
Multi Selector Shoot Mode       : Select Center Focus Point (Reset)
Multi Selector Playback Mode    : Zoom On/Off
Multi Selector                  : Do Nothing
Exposure Delay Mode             : Off
CL Mode Shooting Speed          : 5 fps
Max Continuous Release          : 200
Auto Bracket Order              : 0,-,+
Auto Bracket Mode M             : Flash/Speed
Func 1 Button                   : None
Preview Button                  : Preview
Assign Bkt Button               : Auto Bracketing
Command Dials Change Main Sub   : Autofocus Off, Exposure Off
Command Dials Menu And Playback : Off
Command Dials Aperture Setting  : Sub-command Dial
Release Button To Use Dial      : No
Standby Timer                   : 1 min
Self Timer Time                 : 10 s
Self Timer Shot Interval        : 0.5 s
Self Timer Shot Count           : 1
Image Review Monitor Off Time   : 4 s
Live View Monitor Off Time      : 10 min
Menu Monitor Off Time           : 1 min
Shooting Info Monitor Off Time  : 10 s
Flash Sync Speed                : 1/250 s
Flash Shutter Speed             : 1/60 s
Modeling Flash                  : On
Playback Monitor Off Time       : 10 s
Multi Selector Live View        : Reset
Shutter Speed Lock              : Off
Aperture Lock                   : Off
Movie Shutter Button            : Take Photo
Flash Exposure Comp Area        : Entire Frame
Auto Flash ISO Sensitivity      : Subject and Background
Movie Func 1 Button             : None
Movie Preview Button            : Index Marking
Func 1 Button Plus Dials        : Choose Image Area (DX/1.3x)
Preview Button Plus Dials       : None
Assign Movie Record Button Plus Dials: None
Fine Tune Opt Highlight Weighted: 0
Dynamic Area AF Display         : On
AF Point Illumination           : On During Manual Focusing
Store By Orientation            : Off
Group Area AF Illumination      : Squares
Matrix Metering                 : Face Detection On
Live View Button Options        : Enable
AF Mode Restrictions            : AF-C
Limit AF Area Mode Selection    : Auto-area, Group-area, 3D-tracking, Dynamic area (153 points), Dynamic area (72 points), Dynamic area (25 points)
Lens Focus Function Buttons     : AF Lock Only
Vertical Multi Selector         : Same as Multi-Selector with Info(U/D) & Playback(R/L)
Assign MB-D17 Func Button       : Center-weighted Metering
Assign MB-D17 Func Button Plus Dials: None
AF-On Button                    : AF-On
Sub Selector                    : Focus Point Selection
Sub Selector Center             : AE/AF Lock
Sub Selector Plus Dials         : None
Assign Movie Subselector        : AE/AF Lock
Assign Movie Func 1 Button Plus Dials: None
Assign Movie Preview Button Plus Dials: None
Assign Movie Subselector Plus Dials: None
Sync Release Mode               : Sync
Three-D Tracking Watch Area     : Normal
Subject Motion                  : Erratic
AF Activation                   : AF-On Only
Shutter Release Button AE-L     : Off
Assign MB-D17 AF-On Button      : Same as Camera AF-On Button
Func 2 Button                   : Rating
Assign Movie Func 2 Button      : None
Roll Angle                      : 1.8
Pitch Angle                     : -22.6
Yaw Angle                       : -88.5
Nikon Metering Mode             : Center
Noise Reduction                 : Off
Color Balance Version           : 0225
Lens Data Version               : 0204
Exit Pupil Position             : 93.1 mm
AF Aperture                     : 3.1
Focus Position                  : 0x11
Focus Distance                  : 0.71 m
Lens ID Number                  : 50
Lens F Stops                    : 7.00
Min Focal Length                : 106.8 mm
Max Focal Length                : 106.8 mm
Max Aperture At Min Focal       : 2.8
Max Aperture At Max Focal       : 2.8
MCU Version                     : 53
Effective Max Aperture          : 3.3
Retouch History                 : None
Image Data Size                 : 12369286
Shutter Count                   : 45253
Flash Info Version              : 0108
Flash Source                    : None
External Flash Firmware         : n/a
External Flash Zoom Override    : No
External Flash Status           : Flash Not Attached
External Flash Ready State      : n/a
Flash Compensation              : 0
Flash GN Distance               : 0
Flash Group A Control Mode      : Off
Flash Group B Control Mode      : Off
Flash Group C Control Mode      : Off
Flash Group A Compensation      : 0
Flash Group B Compensation      : 0
Flash Group C Compensation      : 0
Multi Exposure Version          : 0101
Multi Exposure Mode             : Off
Multi Exposure Shots            : 0
Multi Exposure Auto Gain        : Off
High ISO Noise Reduction        : Normal
Power Up Time                   : 2023:03:25 13:50:29
AF Info 2 Version               : 0101
Contrast Detect AF              : On
AF Area Mode                    : Contrast-detect
Phase Detect AF                 : Off
Primary AF Point                : (none)
AF Points Used                  : (none)
Contrast Detect AF In Focus     : No
File Info Version               : 0100
Memory Card Number              : 0
Directory Number                : 111
File Number                     : 8938
AF Fine Tune                    : Off
AF Fine Tune Index              : n/a
AF Fine Tune Adj                : 0
AF Fine Tune Adj Tele           : 0
Retouch Info Version            : 0200
Retouch NEF Processing          : Off
User Comment                    : 
Sub Sec Time                    : 81
Sub Sec Time Original           : 81
Sub Sec Time Digitized          : 81
Flashpix Version                : 0100
Color Space                     : sRGB
Exif Image Width                : 5568
Exif Image Height               : 3712
Interoperability Index          : R98 - DCF basic file (sRGB)
Interoperability Version        : 0100
Sensing Method                  : One-chip color area
File Source                     : Digital Camera
Scene Type                      : Directly photographed
CFA Pattern                     : [Red,Green][Green,Blue]
Custom Rendered                 : Normal
Exposure Mode                   : Manual
Focal Length In 35mm Format     : 157 mm
Scene Capture Type              : Standard
Gain Control                    : Low gain up
Contrast                        : Normal
Saturation                      : Normal
Sharpness                       : Normal
Subject Distance Range          : Unknown
GPS Version ID                  : 2.3.0.0
Compression                     : JPEG (old-style)
Thumbnail Offset                : 18052
Thumbnail Length                : 12249
Creator Tool                    : NIKON D500 Ver.1.20
Rating                          : 0
MPF Version                     : 0100
Number Of Images                : 3
MP Image Flags                  : Dependent child image
MP Image Format                 : JPEG
MP Image Type                   : Large Thumbnail (full HD equivalent)
MP Image Length                 : 804969
MP Image Start                  : 12551680
Dependent Image 1 Entry Number  : 0
Dependent Image 2 Entry Number  : 0
Image Width                     : 5568
Image Height                    : 3712
Encoding Process                : Baseline DCT, Huffman coding
Bits Per Sample                 : 8
Color Components                : 3
Y Cb Cr Sub Sampling            : YCbCr4:2:2 (2 1)
Aperture                        : 7.1
Blue Balance                    : 1.384766
Image Size                      : 5568x3712
Megapixels                      : 20.7
Red Balance                     : 2.452637
Scale Factor To 35 mm Equivalent: 1.5
Shutter Speed                   : 1/250
Create Date                     : 2023:09:30 15:21:12.81
Date/Time Original              : 2023:09:30 15:21:12.81
Modify Date                     : 2023:09:30 15:21:12.81
Thumbnail Image                 : (Binary data 12249 bytes, use -b option to extract)
Preview Image                   : (Binary data 98464 bytes, use -b option to extract)
MP Image 3                      : (Binary data 804969 bytes, use -b option to extract)
Auto Focus                      : On
Lens ID                         : AF Micro-Nikkor 105mm f/2.8D or Sigma Macro 105mm F2.8 EX DG
Lens Spec                       : 105mm f/2.8 D
Circle Of Confusion             : 0.020 mm
Depth Of Field                  : 0.011 m (0.702 - 0.714 m)
Field Of View                   : 11.2 deg (0.14 m)
Focal Length                    : 105.0 mm (35 mm equivalent: 157.0 mm)
Hyperfocal Distance             : 77.28 m
Light Value                     : 10.5

[walt.farrell]

Also, in case it's relevant, JPEGQualityEstimate appears to be a tag/value calculated by ExifTool, not an actual value embedded by the application that produced the file. It's documented by ExifTool as an estimate of the IJG JPEG quality setting for the image, calculated from the quantization tables.

7 minutes ago, Hangman said:

and it would appear that uploading to the forum is adding the PHP GD Library comment to the EXIF data since it doesn't appear in your zipped file but it does in your unzipped file.

That would make sense, as the forum is probably implemented using PHP software and functions, which would be involved in saving and converting uploaded attachments.

[Hangman]

26 minutes ago, walt.farrell said:

Also, in case it's relevant, JPEGQualityEstimate appears to be a tag/value calculated by ExifTool, not an actual value embedded by the application that produced the file.

Though consistent with the JPEG quality values when exporting from Affinity apps. I think all we've really demonstrated here going back to the original question is that the quality value for the out-of-camera JPEG when using the optimal JPEG setting is shown as 100 vs the value shown when uploaded either to this forum or to the Nikonians forum.

32 minutes ago, walt.farrell said:

That would make sense, as the forum is probably implemented using PHP software and functions, which would be involved in saving and converting uploaded attachments.

It is, the Invision Community forum is PHP based so I think it makes perfect sense...

[v_kyr]

Well, the Nikonians forum and galleries do use PHP based services too (same as the Affinity PHP driven forum here) and also for image sharings & previews.

• https://www.nikonians.org/about/client-image-collaboration

Quote

Viewing & downloading NEF, DNG or TIFF images

When you are viewing raw files or TIFF's, JPG representations of these images are created "on the fly". The original file is also accessible and can be downloaded via a small icon below the image.

Under NEF, DNG or TIFF images an additional icon is shown for direct download of the original file.
If the image is located in an album with download enabled, a download button (for JPG download) is shown under it as well.

The above already implicitely tells that JPG representations of images are created on demand (the fly). So in order to others there to see your orig images they have to use the bottom download button (orig image link) there for downloading and previewing locally on their system.

 

Other than that, check your in Affinity as default setup JPG compression quality, if rerouting JPG images.