500D Anti-Aliasing?

Alan Sandham

Alan Sandham

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Alan
Edit My Images
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Just looking to see if anyone has a solution to this problem. When you get lots of straight lines as in this bridge, the (I'm told) anti-aliasing problem results in jagged lines. Yet when the image is magnified, everything is pin-sharp, but then the image is too big for the screen!


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I find this a bit frustrating as reducing the pixel size of the image reduces the sharpness. Andy West was suggesting a problem with too high a pixel count on an APS-C sensor. Anyone have any suggestions??
 
The fact that the problem disappears when the image is enlarged shows that it's a viewing problem (screen jaggies?) rather than an aliasing issue relating to the sensor.

That is a problem relating to the coicidence of very small details when they clash with the pixels and create interference patterns (moire) and the anti-aliasing filter fixes that by effectively bluring very fine detail. The level at which these filters operate appears to be a closely guarded secret, perhaps because it means that the ultimate resolution achievable (Nyquist frequency) is limited by the filter and is therefore somewhat lower than the pixel count, on which most sales seem to be based.
 
Thanks for that advice. You have obviously done more research on this! I think someone said before that this is more of a screen display issue rather than the camera, but it's the same on my laptop and also when viewed on my 21inch Samsung desktop monitor. I wonder if it's the same when viewed on a TV screen. I'll have a look!:thumbs:
 
Alan Sandham said:
Thanks for that advice. You have obviously done more research on this! I think someone said before that this is more of a screen display issue rather than the camera, but it's the same on my laptop and also when viewed on my 21inch Samsung desktop monitor. I wonder if it's the same when viewed on a TV screen. I'll have a look!:thumbs:
Click to expand...

This is usually a software thing, rather than hardware/screen related.

If you post your image processing chain up here, someone with more knowledge of that stuff than I might be able to shed more light.
 
I'm just using Photoshop Elements 8. The only thing I have done with the image is to reduce it to 800px wide to get it on to the TP gallery.
 
swordjo said:
Are you sharpening after resizing?
Click to expand...

No, havent done anything to it as yet. Just got back from holiday and found a few like this. Quite frustrating. When I resize to a smaller size they look ok at first but looking more closely they lose a lot of detail and sharpness.:|
 
As a general rule of thumb, for web sized pics I always sharpen after resizing, makes a difference to the pics.
 
I'll give it a go and see! Just got back from a 2 week cruise in northern Norway and have around 11gb of photos to go through. Should keep me occupied until Christmas!:thumbs:
 
A quick question Alan......
What image quality setting are you using? (Page 70 of your manual)

Bob
 
I always tend to use large - high quality jpeg mode unless it's something important, then I use RAW. This one was taken in large jpeg
 
Sometimes the size you reduce to can make a difference. An image at 50% or 25% of full size will look OK, but one resized to 43% or 29% will not.
 
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