If you click on 'export image' the application will render your document.
Once the rendering is complete a window with a preview of the image and the option to download it in PNG or PDF format will drop down.
Just below the export icon you'll find a quality selector, clicking it will toggle the quality between 5 options: 0.5x, 1x, 2x, 3x and 4x.
This number indicates the upscale factor, if for example you select 2x you will get a generated image that is 2 times taller and 2 times wider than the 1:1 standard quality (4 times the original resolution). Consequently 3x will generate an image with 9 times the original resolution (3 times taller and 3 times wider) and 4x an image with 16 times the original resolution being 4 times bigger in both directions. 0.5x will generate a smaller image with 1/4 the original resolution, with half the height and half the width.
This parameter also affects the individual fretboard exports.
If you click on 'export image' icon on the fretboard toolbar it will generate an image of that individual fretboard with a transparent background.
This will allow quicker and better inclusion of these images into videos, documents and all situations with a non-white background.
The quality is affected by the quality selector in the toolbar.