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blurry jpg

LinwellyLinwelly Posts: 5,981
edited December 1969 in New Users

I've been wondering what I do wrong when I post my jpgs either in the forums or in my gallery. When I have the png they are nice and clean, when I transform it to jpg and look at it on my screen its still nice and clean. Once I put it up in the gallery or in a forum thread the reduced image is blurry whithout end. Obviously most people achieve clear images in the forums and galleriey so there must be omething obvious I'm missing. Any ideas are welcome

Comments

  • mjc1016mjc1016 Posts: 15,001
    edited December 1969

    I think it has a lot to do with the original size and how much the forum software reduces it. Also, the original 'quality' level will impact how much it will blur when shrunk.

  • SpottedKittySpottedKitty Posts: 7,232
    edited December 1969

    Something to bear in mind — yes, jpg compression can produce an image file much smaller than the original, but it does that by throwing away details that "can't be seen", chopping the image into tiny little chunks and optimising the compression for each chunk. This happens every time you save a jpg image, throwing away more and more of the original picture. It is possible to adjust the compression setting to minimise the damage, but that's only possible if you save manually. The automatic compression used by forum software to compress the already compressed (and perhaps further, again and even more compressed) images we upload can't be adjusted to do this.

    Usually it takes several compression stages to create visible damage to an image, but a lot depends on whether you opt for high compression or high quality when you first save the image as a jpg. The best thing to do is to save the original render in a format like png or tiff that doesn't throw bits away; if you need to do postwork, this is the file you work on. When you're sure all the postwork is done, only then should you save the image as a jpg, using a moderately high quality setting. You'll have to use your judgement and experience when you do this, there is no "one-click" universal solution.

    Also, some programs are just better at jpg compression than others, and note that they don't all have the same default setting. Are you just clicking on "save as jpg", or are you actively selecting a quality level when you save the image?

  • LinwellyLinwelly Posts: 5,981
    edited December 1969

    Thank you for your replies spotted kitty and mjc1016.
    I think I do follow the advice you gave. I do everything in png befor I turn it into a jpg to publish and that I do using Gimp. Where it askes for the quality I put it to 100 %. Up to now I didn't change anything in the additional options.
    The render quality I use for publishing in the galleries or in the forums are

    Pixel Samples X/Y : 8
    Shadow Samples : 32
    Shading Rate : 0.20
    Pixel Filter X/Y : 8
    but mostly
    Pixel Samples X/Y : 12
    Shadow Samples : 32
    Shading Rate : 0.10
    Pixel Filter X/Y : 8

    size about 1200 / 900 pixel or around that

    as I took those from the Forums here as a quality setting, I was hoping to be good with that. And well as long as not compressed its fine. The full size view in the forum does look better than the thumbnail and I wouldn't bother too much if everyone elses renders had the same problem, but mostly I see very clear thumbnails.

  • BeeMKayBeeMKay Posts: 7,019
    edited December 1969

    Can you post an example?
    Thumbnails look a bit blurry most of the time. In the gallery, you can reduce the noise a bit by changing the thumbnail "cutout" from the entire picture to a smaller segment of the picture.
    But the size you create is not that huge, normally the software can handle it.

  • LinwellyLinwelly Posts: 5,981
    edited December 1969

    Ok here is one I did for the new user contest and its in my gallery as well.
    But yes I didn't cut the thumbnails for the gallery up to now ( just found that now that you mentioned it - so thanks for that) maybe that is a better way to put them up

    let-me-tell-you-what-your-future-holds.jpg
    1200 x 900 - 717K
  • 3WC3WC Posts: 1,114
    edited March 2015

    Linwelly said:
    there must be omething obvious I'm missing. Any ideas are welcome

    Yes. It's an "s". (Sorry, couldn't resist) :D

    Post edited by 3WC on
  • LinwellyLinwelly Posts: 5,981
    edited December 1969

    wwes said:
    Linwelly said:
    there must be omething obvious I'm missing. Any ideas are welcome

    Yes. It's an "s". (Sorry, couldn't resist) :D

    hehe, ok maybe I'm missing something less obvious as well %-P

  • prixatprixat Posts: 1,590
    edited December 1969

    The image looks (s)harp to me. :-)

    Which bit looks blurry?

  • LinwellyLinwelly Posts: 5,981
    edited December 1969

    prixat said:
    The image looks (s)harp to me. :-)

    Which bit looks blurry?

    I have the impression the thumnail is blurry. When you open it its fine

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