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05-20-2008, 09:19 PM   #1
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It's settled! K10D LCD 1:1 pixel view

Summary: 12x zoom is 1:1, but the usefulness of 1:1 on that screen is questionable.

So here's what I did. I took a photo. In this case, it was just blackness, but that's irrelevant. I opened it in the GIMP and pasted it full of a 1-pixel horizontal line pattern. Then I cut out a rectangle, zoomed way in, and pixel-penciled the word 'test.' (see below).

Unfortunately, the camera would not display the resulting image.

Then I found jhead, which allowed me to transfer the full JPEG header from one file to another. Problem solved.

Now, at 12x zoom on a K10D, the horizontal lines are perfect 1:1, and I count exactly six lines beside the white box, just as it should be. The problem is that the 'test' text is not perfectly sharp. Viewing a pixel-edited image at that zoom level reminds me of looking closely at the TV. Technically, a standard-def TV can display around 480 lines of resolution, but that doesn't mean those lines will ever be sharp.

So 12x it is, but does it really matter?

Btw, I included step-by-step instructions so that other people can do the test with other camera models. If you need more help, pm me.

Attached Images
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PENTAX K10D  Photo 

Last edited by joefru; 05-21-2008 at 06:00 PM. Reason: to quell the flames
05-21-2008, 02:27 AM   #2
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I was thinking of doing something like this on my K20D.

The text may not be sharp because the dots on the camera display are not neatly aligned like in your LCD screen.

Another idea is to take pictures of the camera display and try to figure out what dots are active and to see if interpolation is made or not.

Maybe try a alternative pixel grid - xoxoxox (on white, one black)
05-21-2008, 09:04 AM   #3
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Just a little correction. A standard TV set can display 562 interlaced lines. A VHS video display an image of 480 lines.
05-21-2008, 03:42 PM   #4
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QuoteOriginally posted by flyer Quote
Just a little correction. A standard TV set can display 562 interlaced lines. A VHS video display an image of 480 lines.
Uh no.

NTSC is 648x486 for the visible area.
D1-NTSC is 720x486. Most tube sets will NOT display that full image due to the mechanical requirements of mounting the tube. Which is why pretty much all source media for NTSC that is of decent quality is this, but still respects the text safe and action safe regions. YEs, technically the spec is 525 lines , but everything beyond 486 is the data carrier and is never displayed unless you play with the vhold on an analog signal to se the black and white bands.

There's also a square pixel version of D1-NTSC. which is 720x540.

Then there's PAL which is 720x486 , 720x576 (the resolution fo the source material that is most common), and 768x576 respectively (pal, d1, and d1 square pix). The max lines is 625, but once again the lines over 576 are used for data, and the TVs don't display them.

05-21-2008, 06:01 PM   #5
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Original post edited.
05-21-2008, 06:43 PM   #6
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Most people calculate it at 6X, unless there's something not being taken into account.

- Andrew

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