Need to define the algorithm for the calculation of the output shape of Resample2d

[lisa0314]

As the spec said, when the target sizes are not specified, the output sizes should be calculated from the options.scales argument.
However, the calculation formula of the output shape is missing currently.
For example,
output_shape[axes[i]] = floor(scales[i] * (input_shape[axes[i]]) for all i in axes
output_shape[j] = input_shape[j] for j not in axes, j in range(0, input_rank)

This issue was raised by @huningxin in WebNN Chromium CL review. Thanks Ningxin!

[fdwr]

floor sounds good to me, to avoid partial pixels, and it's evidently also what the preliminary Chromium implementation is already doing in resample.

• tf.image - NA, lacks a scales option
• torchvision.transforms - NA, lacks a scales option
• ONNX - consistent as it floors

[BruceDai]

Thanks @inexorabletash's reminder comment on #611.

Also this is mentioned in #360 so I think after this lands we can close that issue?

Now I think we may close this one, thanks.