Overview plots remain downsampled despite progressive zooming

[yoda-vid]

The ROI Editor displays progressively zoomed "overview" plots on the top row. Large images are downsampled to reduce loading times when displaying the full image. The progressively zoomed images remain downsampled, however, showing lower resolution images than in the sequenced of "zoomed ROI" plots in the subsequent rows.

One solution is to downsample plots only based on their displayed size rather than the full image size. Loading times would likely be worsened, however, since the full image would need to be accessed even if only part of it is in the viewport.

Another solution is to crop the image to only the zoomed area. The downside is that the image could not be flexibly zoomed in and out.

A long-term solution would be to use a pyramidal image to avoid the need for downsampling, instead using the existing downsampled images in the pyramidal structure.

Todo:

• Test performance of large in-memory images to see whether they need downsampling
• Identify bottleneck for images loaded through Tifffile
• GUI option to adjust downsampling
• Reduce/remove downsampling while zooming