________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ [Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index] RE: [APML]: Picture Window's Blend ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ * To: "'astro-photo@nightsky.com'" * Subject: RE: [APML]: Picture Window's Blend * From: Ben Gomes-Casseres * Date: Fri, 8 May 1998 23:02:11 -0400 * Reply-To: astro-photo@nightsky.com * Sender: owner-astro-photo@nightsky.com ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Steve: Photoshop, too, only does pairwise averaging. Contact Matt Considine on this list, whose "ADDPIX" program can add and average any number of .RAW files. Regards, Ben -----Original Message----- From: Steve Bell [SMTP:sb635@delphi.com] Sent: Friday, May 08, 1998 7:17 PM To: astro-photo@nightsky.com Subject: Re: [APML]: Picture Window's Blend Ben Gomes-Casseres wrote: > > The two methods may not be equivalent. It seems to me that you would be > loosing some fractional information if you "average" by pushing down the > curve from 255 to 128 and then adding, as PS will round the fractions to > integers. With a true average (add and then divide) you shouldn't get this > loss (if PS does the math right...). I encountered this problem when adding > 10 solar eclipse images (i.e. need to push the curve down to 25!). With two > images the loss of information is probably negligible. > I see what you mean. So, if possible, it is always better to do a true average to create the final image, instead of a histogram compression and then an Add. Of course, you can only work with two images at a time with these programs (except Mira A/P, I think). At least this is true with Picture Windows and PhotoPaint. I don't know about Photoshop. I believe you mentioned Matt Considine wrote a DOS program that can do many images at once? Is it available? What format(s) (TIF, GIF, etc) can it handle? BTW, those are some real nice solar eclipse shots. -- Clear skies, Steve Bell mailto:sb635@delphi.com Astrophoto page: http://www.mindspring.com/~sb635 ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ * Prev by Author: RE: [APML]: Picture Window's Blend * Next by Author: [APML]: Internet Service Provider problem * Prev by thread: Re: [APML]: Picture Window's Blend * Next by thread: [APML]: Pushing Kodak Elite II 400 ? * Index(es): + Author + Thread