CCD Camera Aspect Ratio Resampling

CCD CB245 aspect ratio of 1 to 1.29 (19.7 um-wide pixels by 25.5 um-high pixels). Notice the "squashed" distortion of the image because the aspect ratio is not 1 to 1. This image is 242 pixels wide by 252 pixels high. Check your monitor display with test patterns to calibrate monitor height and width to correctly display 1 to 1 aspect ratio images.

There are two way to correct the aspect ratio of the above image.

  1. The image can be resampled to increase the number of vertical pixels from 252 to 326 = (252 * 1.29).
  2. The image can be resampled to decrease the number of horizontal pixels from 242 to 187 = (242 / 1.29). This is the method used to correct the aspect ratio of the CB245 images on this Web site.

Aspect ratio is corrected to 1 to 1 by resampling the image on the left to the width of 187 pixels. This results in a image that is 187 25.5 um-wide pixels by 252 25.5 um-high pixels. Resampling images can be done by Richard Berry's CB245 version 60a or Software Bisque CCDSoft CCD Astronomy Software version 4.00.018. I use CCDSoft for resampling because I can save the image in JPEG format for use on Web pages.

A side note: I operate the CB245 Cookbook CCD Camera in a mode that is 252 horizontal photosites and 242 vertical photosites. Because the way the camera is mounted on the telescope I need to rotate my images 90 degrees to place the north edge of the image at the top of the page. After 90 degrees rotation the images are 242 horizontal pixels by 252 vertical pixels.

Use Test patterns to calibrate monitor brightness, contrast, height and width