Hey guys, I’ve asked a few friends but they don’t seem to know either.
How come when I contract (shrink) a circular selection in Photoshop, the new selection circle is no longer circular in shape, it’s … angulated:
GIMP doesn’t seem to have that problem.
So this is a problem with Photoshop CS4 ?
Earlier version of Photoshop doesn’t have this problem ?
But how can it be a problem with CS4 ?
If shrink selection feature was working in previous version of Photoshop, there should be no need to change the source code. So if the code for shrink selection remains the same, how can it be a Photoshop CS4 problem ?
I really hope it’s not a CS4 problem.
actually i just did a test in CS3 and it’s the same “problem”
…but yes, there are some things in CS4 that worked properly in CS3 and earlier versions
the contract tool isn’t really made for that kind of operations
i’d recommend using
1 select > transform selection > hold alt + shift to resize from center point
2 using shapes and aligning them with each other
cheers
When you contract a selection, Photoshop does not evaluate the current shape of the selection and just make it smaller. It instead (if I remember correctly) evaluates the average direction of selected pixels with regard to the edge, then moves each point of the selection edge x pixels in that direction. Since you’re dealing with discrete pixels instead of an actual shape, the contracted “shape” gets distorted slightly. If you were working with an irregular shape or a geometric one with straight lines, you’d probably never notice it, but a regular curve cannot be manipulated in this fashion if it’s based on a grid, as all raster images are.
As Creeto says, you can get a better result by using select > transform selection, but if you happen to have a hole in your selection that won’t work, since the hole’s location will change, and it’s size will shrink instead of growing, as would happen with contract.
That’s… not good…
sometimes I want exact shrinking (shrink by a pixel amount value that I specify).
I prefer the way it works in GIMP, shrinking a circle selection will shrink a circle selection, it doesn’t deform the selection afterward, not to mention I don’t have a limit of 100 pixel shrink as I would in Photoshop.
I think this is how Photoshop should work. I can’t think of a reason why I would want to contract a circular selection and have it deform like it does in the screen shot.
Better stop before I start an application war.
Thanks for the clarification.
Two options:
Convert your selection to a path (paths pallete, next to layers / channels) and do it with vector tools.
Use layer styles ‘stroke’ set to inside and then load this as a selection.
Neither is a perfect solution 
and that's exactly what you can do by transforming the selection. you can see ALL information "live" in the info panel. pixel amount w/h, percentage w/h etc etc
really, you can't get more exact then that ;)
(edit)
you can also try the technique Ian described above. i made a quick video for you 
(observe, much better quality if downloaded)
So many steps…
It only takes 1 step in GIMP:
The tool should work to the way artist think (to make our life easier) not the other way around. Ironically, you’d expect Photoshop would get it right and GIMP get it wrong scratch head.
(sorry about the dodgy screenshot, I scaled the image down)
There’s no sense in complaining to us about it. Take it up with Adobe. The tool works the way it works.
Right click / transform selection / click and drag while holding Alt+Shift …so easy…sigh
Btw, why are you buying an expensive application like Photoshop, while keeping crap like Gimp installed… doesn’t make any sense to me, unless you like their perfect “shrink” 
I’ve been using GIMP to create software and game interface for my colleagues. It’s been there for me, got the job done hence why I still have it installed.
There are some things in GIMP I like that Photoshop isn’t as good at doing (surprised ? )
It’s crap but at least GIMP doesn’t complain when I move the selection box around an empty layer, or do a filter to an empty layer. 
I’m trying to slowly move into Photoshop, I just can’t stand some of the way it do things.
I guess I’ll just bare with it, I know Photoshop has some very smart snapping abilities which I like, especially for lining up fonts and such.
I’m asking these questions because I’m trying to convert from GIMP to Photoshop.
Surprised you ask? Yes, I am surprised to be honest, because you basically claim here that you’re quite a beginner when it comes to Photoshop, yet you also claim that you know exactly what Gimp does better than Photoshop, but that’s strange, because to know what’s possible in Photoshop you need to be an expert in Photoshop (which you aren’t as you claimed), don’t you agree? 
GIMP doesn’t complain when I move the selection box around an empty layer, or do a filter to an empty layer.
You can “move the selection box around an empty layer” in Photoshop without a problem and as for applying a filter to an empty; why would you like to apply a filter to a layer that is…mmm…empty? That’s like trying to paint air.
I’m trying to slowly move into Photoshop, I just can’t stand some of the way it do things.
I’ve been there many years ago, done that and I talked exactly like you. My advice? Get rid of Gimp and forget ALL about it and ONLY think “Photoshop”. Only then you’ll discover the true beauty of Photoshop which, and I’m going to be honest with you, takes some time to discover, but once all the pieces fit together you will agree that it’s an amazingy well thought out program.
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