Unified sampling provides simple and consistent controls for all rendering algorithms. The number of samples taken for a given pixel is between Minimum and Maximum. The exact value within this range is determined mainly by Quality. However, you can set Cutoff to stop taking more samples if the difference between sample levels is smaller than the cutoff value, even if the number of samples set by Quality hasn't been reached yet.
The rendering time per pixel can be shown in the render region or output to disk using the Pixel Time framebuffer. You can set the upper bound or whitepoint of the pixel time values with the Max Pixel Time (µS) setting on the Diagnostics tab of the .
You can specify the default format for saving render previews and render regions with the Default Save Picture File Type option in your Rendering preferences. This is automatically updated with the last format you specified when saving files.