display resolution problem…"jaggies"

TL
Posted By
Tom_Liles
Jul 19, 2008
Views
472
Replies
5
Status
Closed
Hi Guys,

So, I (think I) have an issue with my display resolution in CS3.

I’m very new to photoshop so please bear with me; but I will try my best to explain the problem:

OK so, images I’ve taken with my DSLR appear fine in iphoto and preview – zooming in, or zooming out, doesn’t alter the appearance of the image’s edges – they appear as I’d expect (at the respective zoom factor).

I have stepped up to Ps (CS3) to play with my photos now, but hold the phone! When I open up an image in Ps the edges of lines are "jaggy."

The typical zoom factor Ps opens up my images at is 33.33% – if I zoom in once (50%), or zoom out once (25%) – the edges appear as they did in iphoto, and preview, i.e., not jaggy. Zoom out once more (16.67%), or zoom in twice from that default open size (66.67%) – and there’s the jaggies back again.
So from the open size (33.33%), every odd number of zooms (in or out) gives me "true" appearance; and every even number of zooms (say, 0 for the default open size, 2 for zooming in twice, -2 for zooming out twice, etc.) gives me jaggies…

Being a newbie, I have no idea what is going on here – or even if "resolution" is the right word to be using regarding this topic – but it seems to me that I might have somekind of display setup problem. I’ll list my system specs below; but why is Ps’s zoom not working the way I’d expect – correctly as it does in my other viewing applications? And how can I fix it?

(not having "true" appearance at any level of zoom is obviously problematic if I want to be looking at sharpening, etc. Not to mention the general "what you see is /not/ what you get"-ness of it all is really frustrating)

Tom’s System:

iMac 24in
OSX 10.5.4
Adobe Photoshop CS3 10.0.1

and I think the video card/display setting might be important so:

ATI Radeon HD 2600 Pro
LCD display type
1920 x 1200 resolution
32 bit color

I apologize if this has come up before, I did search this forum for a similar thread – to no avail. But if it has, any links to that content are greatly appreciated.

OK guys, thanks for your time – and I hope you can help!

Tom
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DR
Donald_Reese
Jul 19, 2008
That is normal behavior at the odd percents like 33,66 etc. always view at 100 percent to see the effects of certain layer effects and sharpening etc.
TL
Tom_Liles
Jul 19, 2008
Hello Donald,

Thanks for the quick reply. Much appreciated.

Really? Wow, relieved to hear I don’t have a problem; and a bit disappointed (photoshop exhibits this behavior) at the same time…

So, if I could ask, why is it that other viewing applications don’t have this snag? Is it that they just don’t offer the "odd percent" zoom magnifications? I guess it must be, as it seems strange that simple old preview, or iphoto, are better at this extremely basic function than Ps is.

Last quick question (if I can): is there any way to have photoshop open images in a default zoom that is an "even" number – i.e., have my opened images appearing "true" from the get-go – without being in too close that I can’t see the whole image; or out too far that there’s the grey canvas space all around the image…
It’s a small thing – but these small things tend to be the ones that annoy the most (laughs)

Anyway…

Many thanks again Donald
WG
Welles_Goodrich
Jul 19, 2008
Just an added point, you get clean views at 100%, 50%, 25%, 12.5%, 6.25% (I’ve never had to go farther). Any other % and Photohshop doesn’t redraw smoothly resulting in the jaggies you’ve noticed.

Opening images in Photoshop seem to either be 100% if they fit on your screen or the biggest size which fits and is one of the percentages in the Navigator button list. I’ve not heard of a single default zoom but that doesn’t mean there isn’t some way.
TL
Tom_Liles
Jul 20, 2008
Thanks Welles,

Much relieved to hear this isn’t some bug I have to fix-up; but rather a feature of Ps’s redraw.

I’ll keep to the even zoom factors to avoid confusion, and have a look-see if I can play about the parameters of the zoom tool…

Incidentally I take pictures with a panasonic dmc-l1 (7.4 Megapixel; 4/3s type lens), my RAW images are usually 3148 x 2350 (according to finder), but this seems to change a little when I open a RAW up in CameraRaw…
As an example; one of those 3148 x 2350 RAW files becomes 3136 x 2352 (@240ppi) when dragged onto the Ps icon – to open it in CameraRaw…this is then the image dimension that is preserved throughout the Ps workflow, unless I clip/trim the image etc…

Being a beginner I’m not sure if that is normal behavior either, but it’s interesting that the 12 lost pixels in the x-dimension don’t reappear in the y. Although I do get 2 extra y-pixels – 10 have disappeared somewhere in the mix!

Anyway, thanks for your time and answers guys.

Tom
P
PeterK.
Jul 21, 2008
Photoshop is more accurate about showing exactly the pixel colours that are on screen. The way preview and other programs work is to show you interpolated images at odd percentages. Say if you had an image that only had 2 colours in it. At an odd percentage your screen can’t show you half-pixels, so a decision must be made. Preview would anti-alias the edges and introduce colours in between the 2 that the image is made up of. That would be showing you false colour that doesn’t really exist in the image. Photoshop, on the other hand, makes the decision to throw out those half-pixels and only present the true pixel colours present in the image, hence you get "jaggy" edges (especially if the edges of the butting colours go up at angles or curve around).

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