The bright horizontal streak coming from the bright star at the bottom of the image is called blooming. It is the result of the overexposure of a star with a CCD camera that does not use an anti-blooming CCD device. The excess illumination causes spill into the adjacent photosites of the transfer row of the CCD device. The transfer row is horizontal is this image.
Most CCD devices used in astromony do not use an anti-blooming CCD device because an anti-blooming CCD device is less sensitive to light than a CCD device that is not anti-blooming. The CCD device used in the CB245 Cookbook camera does not use an anti-blooming CCD device.
The image on the left with the blooming has been croped from 187 wide pixels by 252 pixels high to 187 wide pixels by 226 pixels high thus removing the bottom 26 rows of the image which contain the large blooming streak. JASC Inc. Paint Shop Pro version 4.12 was used for the croping. Also, minor star blooming can be touched up with Paint Shop Pro as was done on the three bright stars in the bottom of the image. Notice in the bottom of the image the three bright egg shape stars are more round in the edited image on the right.
Also, see Blooming vs. Anti-Blooming which is part of the Apogee CCD University.
Use Test patterns to calibrate monitor brightness, contrast, height and width
© 1998-2006 David Haworth