6 Replies Latest reply on Jul 2, 2017 6:00 PM by jacka25948919

    Camera RAW JPEG Output Size

    jacka25948919 Level 1

      Hi All,

       

      Just a quick question. Why is it that when I open a RAW image in RAW Filter, make edits and then use the "Save Image" option to export as JPEG is the file size smaller than when I select "Open Image" and then "Export As" in photoshop itself?

       

      Basically, to give an example, I have a RAW image that I am opening in Camera RAW 9.10, this image is set following this metadata:

       

      Adobe RGB (1998)

      16 Bit

      2456 x 3648 - 20MP

      400 PPI

       

      So i edit in Camera RAW, i click on Save Image and save it as a .JPEG with the following attributes:

       

      Quality 10 Maximum

      Adobe RGB (1998)

      8 Bit

      2456 x 3648 - 20MP

      400 PPI

       

      Final File Size: 2.12 MB

       

      Then I select Open Image in Camera Raw of the same image, and then select "File" "Export as" and save it as a .JPEG with exactly the same attributes as above and the image size that way is 4.91 MB

       

      Maybe I am being a complete idiot, but I cannot understand why there is the difference, and are the Save Image option .JPEG files of less quality or higher compression than opening them in Photoshop and THEN exporting them?

       

      Hope someone can help, because I like to keep both .TIFF and .JPEGs of the edits I make (print and web) and would ideally like to retain the highest quality image each time.

       

      Many thanks

       

      JAck

        • 1. Re: Camera RAW JPEG Output Size
          Stephen_A_Marsh Adobe Community Professional

          The simple answer would appear to be that ACR and Photoshop appear to use different JPEG algorithms, and that “equivalent” settings do not equate to the same file size, nor may the settings always be “equivalent”.

           

          I just tested one random image at JPEG level 12, saving as baseline JPEG from Photoshop (ACR does not offer different format encoding options).

           

          ACR.jpg

          FileSize = 9.5 MB

          269 lines of ExifTool metadata

           

           

          PS.jpg

          FileSize = 10 MB

          289 lines of ExifTool metadata

           

          I then used ExifTool to remove all metadata, however there is still an approx. 500kb difference in file size, even taking metadata out of the equation.

           

          So at level 12, there is only a slight file size difference. When I have time I’ll try level 10 to see if there is a more pronounced file size difference as in your example.

          • 2. Re: Camera RAW JPEG Output Size
            jacka25948919 Level 1

            Hi Stephen,

             

            Interesting, as you say there is still unaccounted for data.

             

            It's curious as well as the images I am trying this with still have quite a significant difference even if I "max" out the settings in PS. I still notice that they are almost double the file size of the Camera RAW output.

             

            For example one I have just tried, direct from RAW, with no alterations or adjustments, just straight copy to .JPEG gives me an Camera RAW output of 6.62 MB (oddly also with richer colours than the PS version in this attempt) and the PS version is 10.2 MB.

             

            Really curious as to what is going on here, especially now that I have noticed colour degradation in the PS export.

             

            Very odd.

             

            Any additional testing and advice is greatly appreciated, and thank you for your input on this so far. 

            • 3. Re: Camera RAW JPEG Output Size
              Stephen_A_Marsh Adobe Community Professional

              The difference is “accounted for” if the two algorithms are not identical. Removing metadata levels the field, all that is left is the binary image data and the base data that a given file format requires for it’s file format.

               

              Generally, if a file is double the size, then it is often 16bpc vs. 8bpc – however this should not be the case for JPEG files.

               

              Are you perhaps applying output sharpening when saving the JPEG from ACR?

               

              I’ll look into this a bit deeper, time permitting.

              • 4. Re: Camera RAW JPEG Output Size
                jacka25948919 Level 1

                This is the thing, maybe I am missing some form of additional layer of modification at output level.

                 

                But looking at settings, everything seems to be normal. The difference remains high no matter which levels I set the quality output at.

                 

                For example, see the screenshots below. F = Camera RAW output, psf = PS output

                 

                 

                What is, as I say, equally odd is the difference in colour, seen here below in the two examples:

                 

                 

                Image on the left is Camera RAW, image on the right is PS output.

                 

                Below are the export settings for each, first Camera RAW and second PS options

                 

                 

                 

                Really not sure what I am doing wrong to have the difference, but the colour properties on the smaller file are more appealing, yet I don't want to be losing data.

                 

                Again, thank you for thinking this through.

                • 5. Re: Camera RAW JPEG Output Size
                  Stephen_A_Marsh Adobe Community Professional

                  Thank you for the detailed reply… To some degree, it does help explain the differences that you are seeing!

                   

                  ACR only has one method to create a JPEG.

                   

                  Photoshop has three common methods to create a JPEG:

                   

                  Save As... (Save as Copy)

                  Export As...

                  Export > Save for Web (Legacy)

                   

                  Not all methods are created equal (by design).

                   

                  When saving from ACR, you are using the “medium-wide gamut” Adobe RGB colour space and saving this colour profile into the image.

                   

                  When using the Export as JPEG option from Photoshop, you may not be saving the Adobe ICC profile into the file, which would account for why colour managed software treats the two images with different levels of visual saturation.

                   

                  Also note that the Export JPEG option uses a % based quality method, not a 1-12 level quality method.

                   

                  Export As is intended for creating web/monitor based images.

                   

                  I would compare Save As to the ACR Save Image option as the two are closer to each other.

                  • 6. Re: Camera RAW JPEG Output Size
                    jacka25948919 Level 1

                    Hi Stephen,

                     

                    It would appear you've identified the rub. Doing it as suggested makes the file sizes a lot closer and retains the saturation levels.

                     

                    There is still about 800kb to 1mb difference, but no doubt this is to do with the settings that I am using to save the files and ways I am doing things. I clearly have a LOT more to learn with photoshop!

                     

                    I will continue to learn and play but I think we can call this one resolved for now.

                     

                    Thank you for all of the support and going through it line by line with me, i fear that i was getting stuck in a loop on trying to find the solution to this.

                     

                    Thanks again, and all the best!

                     

                    Jack