Re: [APML] Is DDP Necessary?

[Ray Butler <ray.butler@nuigalway.ie>]

Charles,

As I understand it, DDP is more concerned with preserving image detail 
at both extreme ends of the dynamic range, than with specifically 
accentuating faint nebulosities. DDP may indeed have the desired affect 
on nebulosity at the faint end of the dynamic range, but its most 
impressive use seems to be in simultaneously holding detail in bright, 
dense regions, like the centres of galaxies and very bright nebulae.

However, since it is just a manipulation of the gamma/contrast curve, 
you can achieve similar results with manual curves adjustments.

I'm not sure which software packages come with DDP pre-enabled. However, 
DDP is easily programmed in an environment like IRAF or IDL, so my own 
preference would be "roll my own" DDP over manual curve shaping.

Ray "who's seen ESO press release images which used DDP - a case of the 
professionals adopting an amateur technique" Butler



Charles Shahar wrote:

> Hi Everyone:
>  
> I was wondering whether members feel Digital Development Process (DDP) 
> is necessary. I have become rather adept at pulling out faint details of 
> nebulosity using the PhotoShop curves and levels tools. Will a DDP 
> filter be more efficient in stretching out faint details, or should I 
> trust my manual tweaking more? If someone feels DDP will get better 
> results, please let me know what software you recommend for achieving 
> it. Thanks,
>  
> -Charles
> 
> 
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-- 
Dr. Ray Butler (ray.butler@nuigalway.ie || ray@physics.nuigalway.ie)
Lecturer, Dept. of Physics || Computational Astrophysics Laboratory
National University of Ireland, Galway, University Road, Galway, Ireland.
Tel: +353-91-524411 ext. 3788   FAX: +353-91-525700

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