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Thread: JPG backdrop loading speed?

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    Kenni's Avatar
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    Question JPG backdrop loading speed?

    Hi all,

    I have an issue with the loading speed of backdrops on my Amiga. I've just done a clean install of AmigaOS 3.1.4 on my Amiga 1200 with a Blizzard 1230 IV with 128MB RAM and a 32GB CF card.

    I've installed glowicons and have set the resolution to 640x512 @ 256 colors, as they seem to look the best with 256 colors. I'm happy with the booting time, speed and the overall responsiveness of the system at this resolution.

    However, I've created a JPG image with a resolution of 640x512 and have attempted to use it as a backdrop through Wbpattern. The created file is fairly small, around 80KB, but it takes 25-30 secs to load/appear on boot(!!!). It doesn't seem to be an I/O limitation, as the CF isn't busy much of this time. Once the backdrop has loaded/is appearing, the overall speed of the system is fine.

    I've used the DT-JPEG as datatype.

    Can anyone give me a hint on how to fix this? Should I use another file format (PNG/LMBM/IFF), another JPG datatype, optimize the JPG somehow, or?

    Thank you in advance.

    Best regards
    Kenni

  2. #2
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    davideo's Avatar
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    I've always used IFF files that match the resolution and depth of Workbench because I found they loaded up quicker.

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    confusion's Avatar
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    JPEG needs to be uncompressed before loading into chipmem, and this is a pretty computationally heavy task, especially for 030.
    I think that bmp file will be the best, as it does not encode or compress picture in any way, but I may be wrong (as far as i remember, bmp keeps picture in chunky format, so it needs to be converted to planar).

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    martorellcarles's Avatar
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    I would say the same than davideo and confusion, my advice is avoid JPEG (And compressed formats in general) if you don't have a 060 at least
    Last edited by martorellcarles; 28th January 2020 at 18:55.

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    Kenni's Avatar
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    Quote Originally Posted by confusion View Post
    JPEG needs to be uncompressed before loading into chipmem, and this is a pretty computationally heavy task, especially for 030.
    Bingo! This makes perfectly sense. Converting the file into uncompressed IFF in 256 colors improved the loading time from ~25-30 secs down to ~5 secs

    I did a bit of testing in terms of getting the best output quality. While PPaint 7.1 directly on the Amiga did get the job done, XNView MP did a better output with the Floyd Steinberg dithering-algorithm.

    Thanks a lot for the quick responses.

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    conert it like steve says itll be easier for the machine to load
    i have got too much hardware,it would only hurt your eyes to look at it here

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    Hello,

    another thing! With 256 color Workbench, the bandwidth of the AGA chipset is at its own limit; all the operations on your Amiga will slow-down (a bit or more).
    You can use 128 colors (=7 bitplanes, one is spared and the system is faster a bit), and your picture, if well converted look very similar to 256 colors!

    Regards
    Stefano

    update ----

    i have just forgotten that i have done this

    http://www.amibay.com/showthread.php?104727-DTView2

    that is ok for your task! The last version of this program, let's the user to save the picture, as ILBM, remapped with the colors of the public screen (i.e. Workbench screen), where the picture is displayed!
    After this job, you can play with this program as you wish!

    Read the README file inside the package!
    Last edited by vibros; 31st January 2020 at 11:13.

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    just a quick question ... how do you change the wallpaper from an 8 panel display to one solid picture? I can't find a setting for this change.

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    quantum8's Avatar
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    Quote Originally Posted by rmadden View Post
    just a quick question ... how do you change the wallpaper from an 8 panel display to one solid picture? I can't find a setting for this change.

    Find a wallpaper that matches your screen resolution, or edit the image to match it.

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