JPNG

Richmond Mathewson richmondmathewson at gmail.com
Fri Aug 11 03:29:49 EDT 2017


In theory that sounds both impressive and useful . . .

But, what, apart from your stack can read the format/compression method 
properly.

Also, for the sake of argument: LiveCode can export images in the .PNG, 
.JPG, .GIF and the (horribly obscure ?) .PBM formats.

Can your stack export a JPNG image?

And, if, so; what will read it?

AND this:

"This may even result in a larger data size than the original when 
decompressing."

doesn't bode well.

Richmond.

On 8/11/17 2:56 am, hh via use-livecode wrote:
> JPNG (named using JPEG and PNG) is not an image format but a compression method.
> We use the file ending ".lcjpng" for that.
>
> It takes features from both JPEG (setting JPEGquality to compress the imageData
> and from the PNG compression the alphaData/transparency). It saves the alphaData,
> optionally the maskData, and the JPEG-compressed imageData in one file. The
> JPNG-compressed image has here, using a JPEGquality of 80, around 25% of the
> PNG-compressed size.
>
> So this may be interesting for people who wish to compress (significantly in
> size) the PNG-images containing transparency in their stack/standalone and
> decompress only some images for "current" use.
>
> Compression/Decompression is very fast.
>
> See stack "JPNG" via the "Sample stacks" of the LC toolbar or (slower) here:
> http://livecodeshare.runrev.com/stack/841/JPNG
> This sample stack compresses to files or to (numbered) custom properties.
>
> Note: I don't use the JPNG data structure of js or objC, but you can easily
> convert it to that.
>
>
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