The latest Copyfish update adds desktop OCR support. You can now use the Copyfish browser extension to OCR anything on your desktop with the OCR.space OCR API. See the screencast below on how it works.
To trigger the desktop capture, right-click the Copyfish icon, select Desktop Text Capture. This selection happens locally in your browser, nothing is sent back to any server. Now that the image is displayed in your browser, everything works as usual: Click the Copyfish icon in the toolbar and select the text to extract, and Copyfish does its work.