So... the source image that you are cropping... is it starting out as a single
multi-part exr (each "part" being what we call a "subimage")?
And you are trying to crop each subimage to the same ROI?
I feel like the crucial bits might be right before or after the quoted code.
Do you think you could boil it down to a complete program (or function) that
shows all the steps you are performing, that I can try on this end?
Also, you don't say what version of OIIO you are using. I want to make sure you
aren't bumping into some long-ago-fixed bug.
-- lg
> On Apr 7, 2020, at 1:03 AM, Sven Steinbauer <s...@themill.com> wrote:
>
> Hello,
>
> I am working on adding multi-image support to our application and this is
> going well so far. However I am looking to add in cropping to the multi-image
> also. Originally the crop was done like this:
>
> ImageBuf src("src", spec, scratch);
>
> // Calculate the ROI here.
>
> // crop
> ImageBuf full("full", spec);
> ImageBufAlgo::crop(full, src, roi);
> bool ok = full.write(filename.toStdString(), "exr");
>
> When writing out the multi-image I am following the documentation
>
> for (int s = 0; s < orig_fb_count; s++) {
> if (s > 0) { // Not needed for the first, which is already open
> out->open (filename.toStdString(), specs[s],
> ImageOutput::AppendSubimage);
> }
> out->write_image (TypeDesc::BASETYPE(specs[s].format.basetype), scratch +
> xoffset);
> xoffset += specs[s].image_bytes();
> }
>
> scratch is a char pointer to the image data, where the images are stored
> contiguously. This part has worked fine. So I tried to crop the data like so:
>
> ImageBuf src("src", specs[s], scratch + xoffset);
> // set spec roi to bbox
> // crop
> ImageBuf full("full", specs[s]);
> ImageBufAlgo::crop(full, src, roi);
> //full.get_pixels(ROIroi, TypeDescformat, void *result
> if (s > 0) { // Not needed for the first, which is already open
> out->open (filename.toStdString(), full.spec(),
> ImageOutput::AppendSubimage);
> }
> out->write_image (TypeDesc::BASETYPE(full.spec().format.basetype),
> full.localpixels());
>
> Which compiles and runs, but doesn't give me the expected image (it's a mess
> of pixels).
> What would the correct approach be here to crop the images for a multi-image
> EXR?
>
> The ROI seems to contain the expected width and height values, but when
> checking the exrheaders, the data window values are still the full image
> dimensions. I think this is what might be causing the issues. I've tried
> manually setting width and height in the spec, but also without success.
>
> Thanks
>
> SVEN STEINBAUER​
> Senior R&D Engineer
> T
> +44 20 7287 4041
> <http://www.themill.com/>
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--
Larry Gritz
l...@larrygritz.com
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