Hi Christina,
Originally Posted by
Christina S
How do you know, ie; why the specifics for sharpening for downsizing?
I learnt most of what I know about sharpening from Colin - then adapted it a little for what I shoot and threw in what I know about the best sizes to display things here at CiC. This is similar to what I shoot, so the "usual rules" apply ...
Originally Posted by
Christina S
I would like to learn how and why.. Until most recently I never sharpened my photos after downsizing (I only learned that I should do this from this forum).. And I have been using un-sharp mask for downsizing ie 85% Radius 1, Threshold 4... which is a general recommendation that I learned from a book I recently read.
The down size to 1000px is so it fits the height of most viewers screens (although small/older laptop users may lose out).
It is preferable if the downsize is at least 2:1 (after cropping) to maintain quality and reduce noise (before sharpening).
I hope that Bud went back to the original image to downsize from, because that would give better quality result than just downsizing (again) from the 1599px height one already posted.
How do I know what values for USM?
Amount aim is 100%, but vary above or below dependent upon :-
image content; lower if lots of very fine, bright detail (can look 'speckly' otherwise)
capture type; lower if jpg.
Radius almost always 0.3px, because 0.2 is too narrow and 0.4 begins to risk seeing halos (meaning 1px is way too wide)
Threshold as low as possible.
I try to process my own RAW images so that I can use a threshold of 0 or 1.
It needs to be higher if the original was a jpg capture (e.g. 2 - 4), or if high iso and/or underexposure corrected in PP and/or severe cropping have occurred.
Quite often I will try a guess and if I don't like the result Ctrl+Z undoes it and I have another go.
Originally Posted by
Christina S
The book advises that all photographers use un-sharp mask? Is USM 90% the same as the amount of sharpening?
To clarify; USM is UnSharp Mask (sharpening) - if that's what you're asking, but I may have 'missed the point'.
Cheers,