Yes, Dariusz is probably right and the function that does this is
ImageBufAlgo::resample().
The resample function is very similar to resize, except it just bilinearly
samples between the nearest 4 input pixels, for each output pixel (whereas a
true resize will filter over the whole input region corresponding to the output
pixel).
The resample is lower quality than the resize, but for just generating a quick
preview thumbnail, it may be just fine.
-- lg
> On Jun 29, 2022, at 2:17 AM, Dariusz <[email protected]> wrote:
>
> Hey
>
> Tinkering with the same issue...
>
> I think a faster way would be to get width & height, figure out every nth
> pixel that you want depending on the resolution that you with to get & then
> read only these bytes from arrays.
>
> It wont smooth/resample pixels/etc but u can get quick rough thumbnail this
> way I think?
>
> Regards
> Dariusz
>
> On 28/06/2022 10:22, ████刮 wrote:
>> Hi. may i ask is there a fast way to generate thumbnail image?
>> i have many image with different resolution(from 1080P to 8K or 16K) and
>> different format(jpg, png, exr, psd...etc)
>> there is a existed thumbnail image in Psd format i can use. but for another
>> format i must generate by myself.
>>
>> here is what i was tried:
>> load image with ImageBuf class. then use ImageBufAlgo::resize or resample
>> function to scale it to the target resolution(maybe 480x270). then save the
>> thumbnail image to Disk file.
>> it was worked.
>>
>> i just interesting that is there a "better" or "faster" way to do this?
>> especially for large image.
>>
>> Thanks!
>>
>>
>> ████刮
>> [email protected]
>>
>> <https://wx.mail.qq.com/home/index?t=readmail_businesscard_midpage&nocheck=true&name=%E2%96%88%E2%96%88%E2%96%88%E2%96%88%E5%88%AE&icon=https%3A%2F%2Fres.mail.qq.com%2Fzh_CN%2Fhtmledition%2Fimages%2Frss%2Fmale.gif%3Frand%3D1617349242&mail=15952002677%40qq.com&code=>
>>
>>
>>
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> --
> DARIUSZ MAKOWSKi
> CGI-Photographer
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> [email protected] <mailto:[email protected]>
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