Luminous Landscape Forum

Raw & Post Processing, Printing => Digital Image Processing => Topic started by: button on August 02, 2009, 12:27:07 pm

Title: Best way to downrez in photoshop?
Post by: button on August 02, 2009, 12:27:07 pm

This article takes care of the uprez process (thanks for that, Jeff):

http://www.digitalphotopro.com/technique/s...es.html?start=4 (http://www.digitalphotopro.com/technique/software-technique/the-art-of-the-up-res.html?start=4)

What is the current state of the art in downrez?  All I've ever done is a single step of bicubic sharper.  Are there better methods for achieving maximum sharpness and retention of detail?

Thanks,
John

Title: Best way to downrez in photoshop?
Post by: Schewe on August 02, 2009, 01:09:51 pm

Multiple Bicubic to get close then Bicubic Sharper for the last bit to size...

Title: Best way to downrez in photoshop?
Post by: jjlphoto on August 02, 2009, 04:57:17 pm

Consider converting to CustomRGB with a Gamma of 1.00 (Linear)

http://www.fredmiranda.com/forum/topic/798523 (http://www.fredmiranda.com/forum/topic/798523)

There are benefits to scaling in a truly linear range of tones rather than the steeper 2.2 Gamma.

However, if you are working in 32bit, then Photoshop automatically goes into linear. CS3 only allows Bilinear sampling in 32 bit, not sure what CS4 offers, hopefully more options like Bicubic/Bicubic Sharper, etc.

Title: Best way to downrez in photoshop?
Post by: button on August 02, 2009, 05:12:36 pm

Quote from: Schewe

Multiple Bicubic to get close then Bicubic Sharper for the last bit to size...

Basically, a reverse of uprez, a la multiples of 100% of bicubic, then bicubic sharper when "close" (ie, when you are at a size less then a 100% multiple)?

Title: Best way to downrez in photoshop?
Post by: Jack Flesher on August 02, 2009, 07:21:21 pm

I use 100% incremental multiples of your target size and make the first one the "small" one.  So for example, if your target size is 900 pixels on the long end, and your camera is 5000 pixels across the long end, I suggest you make your first downsize to 3600 pixs.  Then go to 1800, then finish at 900.  I use sharper for the first and last, regular bicubic for all middle steps.  This method is it is easily actionable to get to target resolutions. If you do add a "fit to" step at the end to keep vertical and horizontal images the same max size.  I happen to have a set of 7 web-converter actions pre-packaged -- a "full size" and then a 1200, 900 and 600, one set for high res cameras (20MP and over) and another for medium res cameras (10 - 20MP).  

Cheers,

Title: Best way to downrez in photoshop?
Post by: button on August 03, 2009, 09:42:48 am

Thanks, everyone.

John