For over 2 decades I have photographed with large format film cameras 4x5” and 4X10” panoramic format. Tango drum scans were my preference and usually ordered by clients to reproduce my photography for large-scale purposes. The resulting files were large, 150-350 MB, but the quality was stunning.
When my first website was in production, I struggled with jpeg creation from my large film scans. The resulting downsized files were mushy and soft compared to my originals. I used the traditional advice from Adobe, but the results weren’t working. Hoping that I could avoid rescanning everything, I went to work doing research and testing the different methods of interpolation to come up with a workflow that produced good jpegs for my website.
Gradually, I have moved from film to digital capture and am now shooting a Leaf Aptus on Contax 645 and an Arca Swiss 6X9 view camera. Fortunately, the workflow that I developed for web jpegs from large film scans also works well for high-resolution digital capture. The following is my technique that I have automated in a Photoshop Action. I hope it will work for you.
In Photoshop, open your finished hi-res .tif or .psd file.
Duplicate the file (Image>Duplicate) and close your original.
Sharpen the file (Filter>Sharpen>Unsharp Mask) with the following amounts:
Next, fade the sharpening on the luminosity channel (Edit>Fade)
Resize the image (Image>Image Size). Enter your pixel width or height for the maximum side, and set the resolution to 72 dpi. The most important part of my workflow is the interpolation method – Bilinear – instead of Bicubic or Bicubic Sharper.
Sharpen the file a second time (Filter>Sharpen>Unsharp Mask) with the following amounts:
Again, fade the sharpening on the luminosity channel (Edit>Fade)
M ode: Luminosity
Next, convert your file to the colorspace for the web. In Photoshop CS3, (Edit>Convert to Profile)
If you are working in a 16 Bit workflow, convert to 8 Bit (Image>Mode>8 Bits/Channel)
Finally, save your file as a jpeg (File>Save As) or use save for web, (File>Save for web and devices). “Save for Web” will compress your file more than “Save As”, but will also strip any metadata out of your file, so beware.
A few files always require a bit of tweaking with this process. For instance, a huge original may look better reduced in two steps versus the one downsize step. Also, some files may look better with more or less sharpening applied in the sharpening steps.
(Adjust amount 75% - 200%) is the range I use when needed. The Photoshop action that I created has stops built-in to allow adjustment in these areas.