"Wolf" <nomail@nomail> wrote:
> The main issue with the partial images is that Povray writes the image file in a
> non-standard way in order to keep the created image files small, this prevents
> most image manipulation programs from reading the file.
> The file declares itself to contain the data of the complete image (the image
> headers width and height information is set to the full image size), but in
> reality it contains just the number of rows having been rendered by the partial
> image. Most image manipulation programs are trying to read as many data as
> declared in the image header, resulting in an unexpected-end-of-file while

>

> behaviour:
> 8<==================================================
> When rendering a subset of *columns* (+sc/+ec) POV-Ray generates a full width
> image and fills he not rendered columns with black pixels. This should not be a
> problem for any image reading program no matter what file format is used.
>
> When rendering a subset of *rows* (+sr/+er) POV-Ray writes the full height into
> the image file header and only writed those lines into the image that are
> rendered.
> This can cause problems with image reading programs that are not checking the
> file while reading and just read over the end.
>
> If POV-Ray wrote the actual height of the partial image into the image header
> there would be no way to continue the trace in a later run.
> ===================================================>8
>
> The main problem is to find a image manipulation program being able to handle

> file.
>
> Cheers,
> Wolf

Like I explained before, I render partial images in order not to have to render
again for days in case anything goes wrong.
So, in that case it's better to define each partial image at the full height,
and only limit the number of columns. I briefly tested this, and indeed I can
open the partial image in Photoshop! Thanks.

BTW, I guess you meant GIMP is *indeed* able to read a partial-image PNG.

Steven

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