10 Replies Latest reply on Aug 12, 2013 4:53 AM by station_two

    From tif to jpg

    Ghislaineke

      CS6: why does a TIF image saved to Jpg format becomes so small?
      tif = 292700 kB becomes Jpg = 936 kB
      Jpg options: large file  Quality 12, format option: Baseline standard.

        • 1. Re: From tif to jpg
          c.pfaffenbichler Level 8

          Jpg is a destructive compression method, so the files can get significantly smaller compared to the uncompressed data but also worse (loss of details and introduction of artifacts).

          • 2. Re: From tif to jpg
            Ghislaineke Level 1

            Yes jpg is destructive but in earlier versions of CS at school they never saved so small. Is there a difference  with earlier versions of SC, CS3 versus CS6?

            • 3. Re: From tif to jpg
              c.pfaffenbichler Level 8

              The result of ther compression also depends on the image content.

              What is it?

              • 4. Re: From tif to jpg
                Ghislaineke Level 1

                The CR2 file was 26111kB. After changing several things an working on the picture, i saved it as a tif; then i changed some details untill for me the picture was good. So i wanted to save it as finished as a jpg file. It became JPEG 936 kB. I expected something as 3Mb...

                • 5. Re: From tif to jpg
                  c.pfaffenbichler Level 8

                  So what is the image content, large areas with little contrast for example?

                  • 6. Re: From tif to jpg
                    Ghislaineke Level 1

                    Yes it has +/- 40% large area with deep blue water, +/- 40% large area with green trees, ans a  jetski-ër performing his hobby on the water.. on a canal. (Sorry  english is a bit difficult for me)

                    • 7. Re: From tif to jpg
                      Level 5

                      Let me over-simplify it for you:

                       

                      Imagine you take a photograph of a completely white wall, nothing but white pixels.  Even if you had a TIFF file about 20 MB from a medium format digital camera, the JPEG is going to be able to compress it to near nothing, because it can  "describe"/"depict" the compressed image as "nothing but white pixels in every direction", or 5500 x 17,000 = 93,500,000 white pixels.  The compression would be brutal because the image could be represented by a very short "description" in a very small compressed JPEG file.

                       

                      On the other hand, if you were to take a photograph of some 10 million tiny ants bunched up together into a tightly compact mass with the same camera, even at the highest compression (lowest quality level), 93,5 million different pixels have to be described, therefore the description would have to be incredibly detailed and long, resulting in relatively little compression and a very large file.

                       

                      In your particular example, the vast spaces of blue water can be described with a relatively few zeros and ones, thereby producing your very small JPEG.

                       

                      Do an experiment:  create a very large file of a single color with the paint bucket, say my example above: a rectangle 5,500 pixels wide by 17,000 pixels high.  Save it as a TIFF and note the size of the file.  Now save a JPEG copy of the same file as a JPEG with moderate compression.  You'll see the size of the JPEG copy shrink to a very little size.

                       

                      Personally, I avoid JPEGs like the proverbial plague because there is ALWAYS a loss of quality, to whatever different degrees.  I only generate a JPEG copy when specifically asked for that format by a third party.  Since I'm concerned with high quality photographic prints and not at all with web images, I stay in the PSB, PSD and TIFF formats.

                       

                      Hope that makes it clearer to you.

                      • 8. Re: From tif to jpg
                        Level 5

                        Hey, you just awarded yourself the points for a correct answer instead of giving them to Christoph Pfaffenbichler for solving your question.  

                        • 9. Re: From tif to jpg
                          Ghislaineke Level 1

                          Yes i know i awarded myself .  I didnt mean to.  I wanted to say thanks to c.pfafenbichler for his answer( and now i do not know how to do it, lost him..),I never in my life was on a forum before... and then not simpel... and my language is dutch
                          Thank you for your very clear explanation. I will experiment... Now i am persuaded that the problem is not my CS6 English version (and my new laptop) versus earlier versions of Photoshop..and that there was not  someting simpel i had to check...

                          • 10. Re: From tif to jpg
                            Level 5

                            Uw beheersing van de Engelse taal is veel beter dan mijn Nederlands, hoewel ik kan het mooie Nederlandse taal goed begrijpen.