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    #11
    I was put off png when I found they did not display on my laptop. No idea why but from the net I did not seem to be the only one. Anyone else had a problem?
    bloggoth

    If everything isn't black and white, I say, 'Why the hell not?'
    John Wayne (My guru, not to be confused with my beloved prophet Jeremy Clarkson)

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      #12
      I remember having problems with .png years ago when using old browsers. If your target users are likely to be using old kit, that could be a consideration.
      Behold the warranty -- the bold print giveth and the fine print taketh away.

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        #13
        Originally posted by Durbs View Post
        PNG is a good choice although you have to be careful of legacy browser support of that format. I've produced sites before that looked great in IE 7/8/FF etc but viewed in IE6 they went pear shaped due to the issues handling the transparency (can be sorted via CSS but something to bear in mind).
        Well I'm not an HTMList, so I wouldn't know.

        Do browsers support JPEGs with alpha channels? I think that was part of the JPEG2000 spec, but again I don't know if any of that version of JPEG is in common use.

        What about vector formats? There's Flash that everybody has, but that's a bit overkill for one image. And then there's SVG, which I don't think anybody has ever used ever outside of a standards committee ;-) Are there any other vector formats you could use that the common browsers would support natively?
        Will work inside IR35. Or for food.

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          #14
          Originally posted by VectraMan View Post
          Well I'm not an HTMList, so I wouldn't know.

          Do browsers support JPEGs with alpha channels? I think that was part of the JPEG2000 spec, but again I don't know if any of that version of JPEG is in common use.

          What about vector formats? There's Flash that everybody has, but that's a bit overkill for one image. And then there's SVG, which I don't think anybody has ever used ever outside of a standards committee ;-) Are there any other vector formats you could use that the common browsers would support natively?
          Unfortunately no, there's no other real alternatives. Think JPEG2000 died because of bickering over who 'owns' jpg.

          Microsoft were working on JPEG XR based on their own HD Photo technology but don't know whether it came to owt. Think it was aimed at photographers anyway, not web graphics.

          Read the following on why JPEG couldn't easily support alpha transparency on http://www.faqs.org/faqs/jpeg-faq/pa...ction-12.html:

          "The traditional approach to transparency, as found in GIF and some other
          file formats, is to choose one otherwise-unused color value to denote a
          transparent pixel. That can't work in JPEG because JPEG is lossy: a pixel
          won't necessarily come out *exactly* the same color that it started as.
          Normally, a small error in a pixel value is OK because it affects the image
          only slightly. But if it changes the pixel from transparent to normal or
          vice versa, the error would be highly visible and annoying, especially if
          the actual background were quite different from the transparent color.

          A more reasonable approach is to store an alpha channel (transparency
          percentage) as a separate color component in a JPEG image. That could work
          since a small error in alpha makes only a small difference in the result.
          The problem is that a typical alpha channel is exactly the sort of image
          that JPEG does very badly on: lots of large flat areas and sudden jumps.
          You'd have to use a very high quality setting for the alpha channel. It
          could be done, but the penalty in file size is large. A transparent JPEG
          done this way could easily be double the size of a non-transparent JPEG.
          That's too high a price to pay for most uses of transparency.

          The only real solution is to combine lossy JPEG storage of the image
          with lossless storage of a transparency mask using some other algorithm.
          Developing, standardizing, and popularizing a file format capable of
          doing that is not a small task. As far as I know, no serious work is
          being done on it; transparency doesn't seem worth that much effort.
          "

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            #15
            Originally posted by VectraMan View Post
            I'd like to hear your technical explanation as to how a lossy compressed image can be uncompressed, reduced in resolution and recommpressed in the same lossy format without losing any quality. And would you really use JPEG for a logo? It tends to make a bit of a mess of sharp edges and blocks of solid colour, being designed for photographs.
            iirc, GIF isn't lossy. RLE

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              #16
              So, what I'm getting from this is that I should use the .ai file to produce .bmp or .png files for the images for my website. Correct?

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                #17
                Originally posted by Badger View Post
                So, what I'm getting from this is that I should use the .ai file to produce .bmp or .png files for the images for my website. Correct?
                Not .bmp - too big, your choices are .png,.jpg,.gif and see what works best for that particular image.

                I always create a whacking great .jpg or png. Say i have my logo file, i'll export the logo as a big 800px width image for web use as i know it'll never need to be displayed at that size. Then i use this logo_original.jpg as the source logo for future web pages and just grab it and resize it to whatever in something like Fireworks.

                Thats worked for me anyway and reason i dont generally use the source vector file each time is i know wherever i am, i'll generally have a package capable of resizing a .jpg/.png and not necessarily have the means to mess with a .ai file.

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                  #18
                  Ok got it, thanks Durbs.

                  All I've got is the .ai file and several .gifs made from the .ai file. I'm not too happy that the guy who created it (a designer no less!) knew it was for a website so should have really known that .gif files were pants for resizing.

                  I have Photoshop and GIMP available so should be able to get the right results.

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                    #19
                    Originally posted by Badger View Post
                    Ok got it, thanks Durbs.

                    All I've got is the .ai file and several .gifs made from the .ai file. I'm not too happy that the guy who created it (a designer no less!) knew it was for a website so should have really known that .gif files were pants for resizing.

                    I have Photoshop and GIMP available so should be able to get the right results.
                    I know it's old-fashioned but couldn't you get a lossless TIFF for transferring between apps? PS and GIMP will of course read them.

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                      #20
                      Originally posted by expat View Post
                      I know it's old-fashioned but couldn't you get a lossless TIFF for transferring between apps? PS and GIMP will of course read them.
                      Yup, TIFF would be a great format to store your original image as an alternative to JPG as its top quality and also, as expat says, universally readable.

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