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09-17-2009, 11:24 AM   #1
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Pentax please REMOVE Anti-Aliasing on K-7 LCD

With the K-7's new hi-res screen, Pentax decided to ANTI-ALIAS zoomed-in images. for all intents and purposes, deliberately ADDING blur to the playback images - making judging critical focus on the K-7 MUCH HARDER than it was on the K20D's considerably "lower" resolution screen.

You can never get to the pixel, which is important if you ever intend to crop your images or simply want to make sure your pictures, (and more-importantly, lenses and AF system) are razor-sharp.

I don't know if this was done to avoid showing the K-7's peculiar pixel noise quality, but what's the point of having and touting a high-resolution screen if you're deliberately filtering out extreme detail? i don't understand any photographic reasons for it, just the marketing ones.

Pentax, PLEASE PLEASE add the option to DISABLE AA for zoomed playback on the LCD in your next firmware update.

.... and please (x2) also put lighting up the top LCD back to my direct control, like I did with the K20D and the EV button. I was under the impression the K-7 was supposed to give us more control over our camera and our images, not less.


Last edited by illdefined; 09-17-2009 at 11:30 AM.
09-17-2009, 11:31 AM   #2
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Aliasing is the result of representing a high-frequency image using a low-frequency screen. Multiple pixels must necessarily by represented by a single pixel. This can be done by simply dropping pixels (which is what my K20D does) or by averaging multiple pixels (which is an anti-aliasing technique).

However, once the frequency of the image matches the frequency of the screen, pixels are one-to-one, and there can be no averaging algorithm applied. Therefore, when an image is zoomed in all the way, there will be no blurring.
09-17-2009, 11:46 AM   #3
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QuoteOriginally posted by Jim Royal Quote
Aliasing is the result of representing a high-frequency image using a low-frequency screen. Multiple pixels must necessarily by represented by a single pixel. This can be done by simply dropping pixels (which is what my K20D does) or by averaging multiple pixels (which is an anti-aliasing technique).

However, once the frequency of the image matches the frequency of the screen, pixels are one-to-one, and there can be no averaging algorithm applied. Therefore, when an image is zoomed in all the way, there will be no blurring.
would you happen to know at what magnification that is? i was under the impression it was 8x on the K20D, but the image is blurry at that magnification on the K-7.
09-17-2009, 12:38 PM   #4
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QuoteOriginally posted by illdefined Quote
would you happen to know at what magnification that is? i was under the impression it was 8x on the K20D, but the image is blurry at that magnification on the K-7.
I thought it was 11x on the K20D, but I could be mistaken. I don't know about the K-7. If the screen on that model has a higher resolution then the zoom factor for 100% will be different.

09-17-2009, 02:10 PM   #5
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On the k20d was 6.7 for 100 %
09-17-2009, 02:52 PM   #6
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QuoteOriginally posted by netuser Quote
On the k20d was 6.7 for 100 %
Actually, I think we were both wrong,and Illdefined was correct. I just did the math. Assuming the K20D's LCD resolution is approximately 230000 pixels, and is 4:3 in aspect ratio, a magnification of 8X shows 1:1 on that screen.
09-17-2009, 03:39 PM   #7
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QuoteOriginally posted by Jim Royal Quote
Actually, I think we were both wrong,and Illdefined was correct. I just did the math. Assuming the K20D's LCD resolution is approximately 230000 pixels, and is 4:3 in aspect ratio, a magnification of 8X shows 1:1 on that screen.
the K-7 screen has 920,000 pixels, so what would the magnification be in that case? sorry, math was never my strong suit.
09-17-2009, 03:45 PM   #8
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You shooting RAW or JPEG? Some cameras use a much smaller / lower res JPEG for the preview when shooting RAW.

09-17-2009, 04:00 PM   #9
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To get a couple contorted things straight ...

1. The K-7 LCD has 640x480 resolution, K20D has 320x240 resolution (multiply and x3 to get the meaningless "dots") ...

2. The LiveView image is produced from a 1536x1024 live stream.

=>
Magnification x2.4 is already 1:1 on K-7, and x4.8 on K20D in LiveView. Higher LiveView zoom levels are interpolated and may appear blurred or coarse.

=>
Magnification x7.3 (x8) is 1:1 on K-7, and x14.6 (x15) on K20D in magnified play mode.

3. When using manual focussing in LiveView on K-7 with zoom modes x8 or x10 (the maximum and special with manual focussing), then K-7 changes its processing pipeline and yields different images (e.g., with much less noise). For this mode, I do not know when an exact 1:1 ratio is achieved. Maybe, a full readout of a partial area is done then. Making the x8 zoom level 1:1 again. This special mode is missing in the K20D!
09-17-2009, 04:01 PM   #10
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But OP is talking about the playback/(p)review image, not the liveview feed.
09-17-2009, 04:19 PM   #11
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QuoteOriginally posted by pingflood Quote
But OP is talking about the playback/(p)review image, not the liveview feed.
My response covered this as well.
I only wanted to straight out some details, without offering an opinion.
09-17-2009, 04:44 PM   #12
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QuoteOriginally posted by falconeye Quote
My response covered this as well.
I only wanted to straight out some details, without offering an opinion.
Thank you Falconeye. always there for the rescue
09-18-2009, 07:21 AM   #13
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QuoteOriginally posted by falconeye Quote
To get a couple contorted things straight ...

1. The K-7 LCD has 640x480 resolution, K20D has 320x240 resolution (multiply and x3 to get the meaningless "dots") ...
What do you mean by "X3 to get meaningless dots?" The K20D's screen cannot 320x240. If that were the case, the total number of pixels would be 76800, when in fact the screen shows about 230000 pixels.
09-18-2009, 07:32 AM   #14
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QuoteOriginally posted by Jim Royal Quote
What do you mean by "X3 to get meaningless dots?" The K20D's screen cannot 320x240. If that were the case, the total number of pixels would be 76800, when in fact the screen shows about 230000 pixels.
That's exactly what he means by "X3 to get meaningless dots"

Each pixel on the LCD screen is made up of 3 "dots" (one red, one green, one blue). 76800 * 3 = 230400.
09-18-2009, 08:27 AM   #15
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76800 x 3 = 230400
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