Re: Saving part of an Image

Hi Maciek,

Going off memory here, but in general you have to supply information about
your image when constructing the header.
You are then you are free to 'feed' the data in a way that is convenient to
you. If you close the file without writing all the data then most
applications will have issues in opening it up since it will be considered
to be corrupt.
You could write a brand new file each time you had a group of tiles come
in, but you would have to control your tile locations so that you always
had a valid rectangular region.
Another alternative would be to simply write out black, say, pixels for the
un-rendered regions.
We have talked about a general checkpointing scheme but I don't think we
got very far with any implementation.
Can you share some more information as to the context of your work? Is it
the case that you want the OS to show you the current state of the render
to a file?

Thanks

-Piotr



On 10 June 2016 at 07:42, Maciek Mostowski <[email protected]> wrote:

> Hi,
> I'm working for Isotropix and recently we wanted to add feature to allow
> saving partially rendered images. This would allow us to preview rendering.
> In order to do so that i'm looking if it's possible to save openexr images
> in "append" mode. In the documentation :
> http://www.openexr.com/ReadingAndWritingImageFiles-1.2.x.pdf
> i found it's possible to save cropped images. In the given example only
> saving scanlines is mentioned. "The classes for reading scan-line-based
> images (InputFile and RgbaInputFile) can also be used to read tiled image
> files" i assume that interface for scanline image will work in the same way
> for writing tiled image ? How it would work afterthat? If i keep image file
> open and write pieces of image bit by bit will i be able to preview the
> image during the processe? Or if i open, write a part of an and then close
> it will i delete the previous data?
> Thanks for hints and any insight in advance,
> Maciek
>
> --
>
>
> *Maciej Mostowski*
> *Research Developer*
> Email: [email protected]
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