Data acquisition systems try to display new image data as quickly as possible. Bespoke systems with full access to underlying operating system resources can use special techniques such as shared memory and tailored data formats. Generic systems will access FITS files to extract an image array and convert to RGB pixels for display. In this vein, the JS9.RefreshImage() routine accepts a FITS file contained in a JavaScript object or array, a typed array, a blob, or string. The refresh rate depends on the speed of the host CPU and the dimensions of the image. Use this demo to test the JS9 refresh rate on your host with data of your choosing.
Click the Choose Files (aka Browse) button and select two or more local FITS files to load. Choose the number of refreshes and click Run Test. The JS9.RefreshImage() routine will be called repeatedly to update the current display with the image pixels from each file in turn. On completion, the refresh rate is displayed.
The squares.tar.gz file contains two FITS images of size 512x512, 1024x1024, and 2048x2048, respectively, which might be useful for purposes of comparison.