Monday, 7 January 2008

Optimizing for the web - continued

After the last post, I spent some time examining different displays of the images, digging into the EXIF data, uploading, downloading and so on. It seems things aren't exactly as I supposed them at first. I also did some reading on Firefox image display.

Here is what I now know (I could still be wrong, though).

As I knew before, Firefox does not use embedded colour profiles when downloading web pages. I'm pretty specific about that part because it appears if I use Firefox as a viewer for files from my computer (using the File: Open File... menu) then it does appear to display using the colour profile. Odd. Can't find info on that part anywhere in Web land.

Oh for Firefox 3, which apparently will work with colour profiles.

The next thing I discovered is that Blogger actually leaves all image data intact, including the full EXIF. When I download the images back to my computer they are identical to the originals I uploaded. So any display problems are related to the browser interpreting the web page.

I also found out that the software I mainly use for generating web images (EasyThumbnails) only preserves EXIF data for JPEGs, not when converting TIFFs. This means most of my blog posts have images with "Unknown" in the colour profile slot (rather than Unencoded that you get when stripping the profile with Photoshop).

Looks like I'll be making some wholesale changes to my web image routine to ensure I get something that looks decent.


  1. Export to sRGB. Almost every browser assumes that you're using that color space, and your images should be consistent across browsers.

  2. Mmmmm....seems that my last (innocent) remark gave You lots of extra work and unanticipated problems. :-)

    Don't quite understand Your last posting: am I reading You correctly in sofar that that You think the browser displays the images based on the info found in the EXIF data, more importantly the EXIF data relating to the color profile slot?

    If that is so, all images posted to the web should carry complete and correct in fo in this part of the EXIF data?

  3. chris - I realised that but I was exploring other aspects of colour profile retention across my web workflow.

    zeus - no, browsers don't read the EXIF either. this led me to even further reading which will be the subject of yet another post on this topic.


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