[bergy]

When I first open a photo in Preview it is nice and sharp .. then almost immediately some sort of filter kicks in and the picture becomes fuzzier. I have tried turning off anti aliasing .. but I think that only applies to text and line art. It is in the PDF prefs anyway.
Does anyone else notice this ... is there any way to stop it from going fuzzy?

[Toyin]

If this happens select view -> actual size (or type apple + zero). Preview will resize images to fit into the window which causes it to sometimes look crappy.

You can change this in the preferences under the image tab to always show the actual size as a default.

[arcticmac]

yeah.. preview likes to make it so that images still look relatively smooth even if you blow them up or shrink them down... there might be a way to turn it off, but the easiest thing for now is simply to view the image at actual size, so that preview feels no need to smooth it.

[bergy]

Originally posted by Toyin:
If this happens select view -> actual size (or type apple + zero). Preview will resize images to fit into the window which causes it to sometimes look crappy.

You can change this in the preferences under the image tab to always show the actual size as a default.

Thanks for the replies
I did as you suggested .. however it has had no effect ... I still get that fuzzying.

[Jacke]

Edit: Should learn to read entire posts...

[Developer]

Originally posted by bergy:
I did as you suggested .. however it has had no effect ... I still get that fuzzying.

The fuzzying is by design. Most people prefer it. You can send feedback to Apple, so maybe they'll add a setting for it <http://www.apple.com/macosx/feedback/>. Until then you have to live with it.

[BWSchultz]

Originally posted by Developer:
The fuzzying is by design. Most people prefer it. You can send feedback to Apple, so maybe they'll add a setting for it <http://www.apple.com/macosx/feedback/>. Until then you have to live with it.

Question:

Why do people prefer fuzzy as opposed to clear/crisp?

Cast my vote for the "I hate the fuzzification of my Preview documents." I always thought it was a flaw in my monitor. Now I know it's just a less that perfect design.

[Developer]

Originally posted by BWSchultz:
Why do people prefer fuzzy as opposed to clear/crisp?

When Preview scales down a picture that basically means it resamples the original at a lower sample rate. You have fewer pixels and each is a sample of the original.

Whenever you sample a signal, the sample rate always has to be at least twice as much as the signal frequency. Let's say you're sampling a sinus curve then you need at least one sample when the curve is up and one when it is down. When the signal frequency is higher then twice the sample rate then artifacts accure. Let's say the signal frequency is exactly the sampling rate, then it might always only sample the sinus curve when it's up which is obviously wrong. Such artifacts are called aliasing.

To avoid this aliasing the portions of the signal with a frequency higher than half the sample rate are filtered out with a low-pass filter.

These high frequency portions are the "crisp/clear high detail" portions you like, but they are also the portions responsible for the aliasing artifacts that most people dislike. It's a tradeoff.

[Brass]

Originally posted by Developer:
When Preview scales down a picture that basically means it resamples the original at a lower sample rate. You have fewer pixels and each is a sample of the original.

So why does it happen to "actual size" images too?

[Developer]

Originally posted by Brass:
So why does it happen to "actual size" images too?

It depends on what you mean by "actual size".

Let's say you scan a 4"x6" picture at 300 dpi and then print it with a printer at 300 dpi, then the printout will be 4"x6" as well. That's "actual size". Your computer screen has not 300 dpi but a resolution of 72 dpi (by definition). Therefore to display the image at the size of 4"x6" on the screen it has to be downsampled.

If you don't downsample the image and display each pixel of the image as one pixel on screen the image will be 300/72 of the original size, i. e. much larger. Though you could consider 1 pixel = 1 pixel as "actual size" as well.

You can switch that in the Preview preferences (disregard DPI in actual size). If you do and images display in 1 pixel = 1 pixel "actual size" no fuzzying occurs.

[Boondoggle]

have you tried turning off anti-aliasing in the Preview prefs?

that is what is happening. The image loads normally and then Preview applies the anti-alisasing as per your prefs. That is why it looks sharp for a second.

bd

[bergy]

Originally posted by Boondoggle:
have you tried turning off anti-aliasing in the Preview prefs?

that is what is happening. The image loads normally and then Preview applies the anti-alisasing as per your prefs. That is why it looks sharp for a second.

bd

As I said in my original post, that was the first thing I tried and it makes no difference ... I think it is for text and line art only as it is in the PDF prefs section of preferences.

There seems to be a highly technical reason why this filter kicks in as explained by some of the replies ,, however, I just wish I could choose for it not to happen. The photos look great for an instant then ... smudge factor filter takes over.

[Chuckit]

Originally posted by bergy:
There seems to be a highly technical reason why this filter kicks in as explained by some of the replies ,, however, I just wish I could choose for it not to happen. The photos look great for an instant then ... smudge factor filter takes over.

That's strange � I think it's the opposite way. I have some photos with a pretty intricate sort of fence pattern in them, and when I first open them at a size smaller than 100%, the fence is all distorted-looking (something like the wavy effect you'll see on such patterns in older video games). Once the smoother resampling kicks in, though, the lines go back to how they should look. It looks to me like a more accurate resampling than the "sharper" one that you like.

Just my observation.

[Brass]

Originally posted by Chuckit:
That's strange � I think it's the opposite way. I have some photos with a pretty intricate sort of fence pattern in them, and when I first open them at a size smaller than 100%, the fence is all distorted-looking (something like the wavy effect you'll see on such patterns in older video games). Once the smoother resampling kicks in, though, the lines go back to how they should look. It looks to me like a more accurate resampling than the "sharper" one that you like.

Just my observation.

It's due to the size at which your viewing the image compared to the actual size of the image (and of course, as Developer mentioned, whether or not the actual size is a 1:1 pixel ratio with the screen).

You're not viewing it at actual size, so you first get a rough over sample of the image, then a finer more detailed sample of the image, which takes a little longer to calculate as it scales the image.

[theolein]

Originally posted by bergy:
As I said in my original post, that was the first thing I tried and it makes no difference ... I think it is for text and line art only as it is in the PDF prefs section of preferences.

There seems to be a highly technical reason why this filter kicks in as explained by some of the replies ,, however, I just wish I could choose for it not to happen. The photos look great for an instant then ... smudge factor filter takes over.

What seems to work is the following:
1. Open the image
2. Open the prefs and select the images tab
3. Uncheck the box "Respect image DPI for 'Actual Size'"
4. Select Actual Size from the view menu or press Cmd-0

I think there is that one actual size that doesn't get smoothed if I see correctly.