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  1. Banned
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    How do I resize images without losing quality?
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  2. Member Cornucopia's Avatar
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    You don't, not counting simple integer changes that can be completely reverseable (e.g. line doubling).

    ALL other forms use interpolation/extrapolation which are guesses. Guesses are never exact and are blends, so you are losing quality.


    Scott
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  3. And the other limited case /exception are vector images , which can scale without loss
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  4. Imagine image 2x2, your original,

    first you resize it using Bicubic resize to 8x8, new pixels are created with different colors, it is in no way same as original, but you might say it looks better. But same thing could actually do a web browser resizer or mediaplayer resizer. Why to make it bigger. Only you want to enhance something, maybe.

    than you resize to 8x8 but using Point (nearest) resize, You make image 16 times bigger but no new information is made, in theory, colors are the same but it makes no sense
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    Last edited by _Al_; 4th Feb 2024 at 20:20.
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  5. original 2x2
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  6. Video Restorer lordsmurf's Avatar
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    Originally Posted by Cornucopia View Post
    You don't,
    But ... but .... AI... and stuff.
    AI!
    AI I TELL YOU!
    Old MacDonald had a farm, AI AI O!
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  7. Member Cornucopia's Avatar
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    Yeah, @pdr, vectors. I just assumed things wouldn't devolve to that level. I do think that some future machine vision/AI codecs may be able to parametrically describe a video scene as objects, which could lead to great efficiency. But think of the encoding computation time!!

    Scott
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  8. Member Cornucopia's Avatar
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    @_AI_, the test for those things is fidelity to the ground truth source (or what the gts would be if if was that size originally), so no I don't think you could say that's better.

    Point resize works great for special cases of block graphics, but lots of other cases not so much.


    Scott
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  9. Originally Posted by Jay123210599 View Post
    How do I resize images without losing quality?
    Resize is very wide term - if you resize image to be smaller then quality lost is unavoidable, if you resize image to be bigger then mathematical perfect formula is point resize (a.k.a. Nearest-neighbor interpolation) but it far from acceptable subjective quality - usually it give worst results.
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