[Image-SIG] Re: 16bit PNG read/write supported ?

[Fredrik Lundh]

Sebastian Haase wrote:

> I am about to start using PIL. We (BioChemistry department
> at UCSF) are dealing with grayscale images that are 16
> bits per pixel (if not floating point).
> I read that the latest (beta) version of PIL should now
> support 16bit TIFF images ...
>
> What is the status regarding 16bit gray images with PNG ?

if I remember correctly, and interpret the code correctly, PIL reads
16-bit monochrome PNG files as mode "I" images (that is, it uses 32-
bit internal storage).

I don't have any 16-bit samples on this box (and no time to google
for them), but roundtripping sure seems to work:

    >>> import Image
    >>> im = Image.new("I", (100, 100))
    >>> im.putdata(range(10000))
    >>> im.getpixel((50, 50))
    5050
    >>> im.save("out.png")

    >>> im = Image.open("out.png")
    >>> im.mode
    'I'
    >>> im.size
    (100, 100)
    >>> im.getpixel((50, 50))
    5050

</F>