9 Replies Latest reply on Mar 14, 2018 3:02 AM by G.Hoffmann

    100MB+ Resize to 1MB

    Zack871024

      I have multiple 100 MB+ psd and tiff files in CMYK. I would like to resize them into 1 MB, 300 ppi and around 10-15 cm in width.

      I tried doing it through image size and re-sampling. But the smallest file size I could get is around 3.9 MB.

      Strangely, if I put the exported 3.9 MB jpg onto a new canvas, and do the export again, the file size could be lowed to around 900KB.

      Is there any quicker way of doing this kind of resizing? Or this is the only way?

      Thanks

        • 1. Re: 100MB+ Resize to 1MB
          c.pfaffenbichler Level 9

          What is the »end-game« here?

          Why CMYK and which Colour Space exactly?

          What file format do you save to?

          Is there significant Ancestor metadata involved?

          Have you tried using File > Export > Save for Web (Legacy) to resize, convert to sRGB and remove metadata in one go?

          • 2. Re: 100MB+ Resize to 1MB
            Mylenium Most Valuable Participant

            Well, are you actually sure you are using the same settings and procedures every time? To me it sounds like you don't and that you are merely experiencing color profiles and other metadata being dropped when you re-import your files in a standard document with no custom color settings and the like. If that works, then logically all you would need to do is strip that information from your other files just as well, possibly by ways of using an action to switch the color settings around and using Save for Web/ Save as Copy or whatever.

             

            Mylenium

            1 person found this helpful
            • 3. Re: 100MB+ Resize to 1MB
              Zack871024 Level 1

              The reason I specify CMYK is because if you save it for web the color space will be converted to RGB. I need these file to be used in print, that is why I need it in CMYK and with 300 ppi. The file format I have to save to is JPG.

              • 4. Re: 100MB+ Resize to 1MB
                Zack871024 Level 1

                Yes indeed, I use the exact same settings every time I import the jpg I exported in the first step. The new canvas I created in also 300 ppi, in CMYK.

                • 5. Re: 100MB+ Resize to 1MB
                  c.pfaffenbichler Level 9

                  Is there significant Ancestor metadata involved?

                  • 6. Re: 100MB+ Resize to 1MB
                    Zack871024 Level 1

                    Nope there are not. I checked it with XMP in photoshop.

                    • 7. Re: 100MB+ Resize to 1MB
                      c.pfaffenbichler Level 9

                      Can you provide one of the files?

                      • 8. Re: 100MB+ Resize to 1MB
                        Zack871024 Level 1

                        I am really sorry, I wish I could that would be a lot easier. Unfortunately, I can not send out my client's files.

                        The image was taken by a Phase One IQ180 at 6179x5672 @ 1355.73 Pixel/Inch btw.

                        • 9. Re: 100MB+ Resize to 1MB
                          G.Hoffmann Level 4

                          An embedded CMYK profile would consume 1.5...2.5 MByte,

                          e.g. 1.74 MByte for ISOCoated-v2-eci.

                          The embedded profile will be part of the image file (PSD, TIFF,

                          JPEG), it is not added as Metadata by XMP.

                           

                          The JPEG compression for RGB images is based on splitting

                          RGB into YCbCr, where Y is the Lightness and Cb,Cr are residual

                          colors (comparable to a and b in Lab).

                          The numerical compression loss for Y is low, but very high for Cb,Cr.

                          One reason is the so-called subsampling, where Cb (and Cr) for

                          each group of 4 pixels is considered as one value. This CbCr com-

                          pression doesn't affect the visual quality very much.

                           

                          But CMYK cannot be split into Y and residual colors, because this

                          would destroy the black generation. Therefore each channel has

                          to be treated as a Grayscale image, applying the same low-loss

                          strategy as for Y.

                          Therefore the filesize of a CMYK JPEG is not only larger by factor

                          4/3 compared to RGB, but in fact much larger for the same visual

                          quality.

                           

                          Best regards

                          --Gernot Hoffmann

                          1 person found this helpful