Monitor size/resolution vs. pixel pitch

[Berek]

While reading reviews about a couple of Doublesight DS-263N H-IPS 26" monitors I ordered recently, I came across some confusing information regarding the density of pixels and the pixel pitch. Since these are 26" monitors, it was my assumption that everything would be slightly larger in appearance than a 24" screen, which is what I had previously. I loved my original Dell 2405WFP, so I knew these would be close.

I would have bought a few Dell 2408WFP's, as I prefer the 24" screen size, but they have some severe problems in input lag and visual artifacts, much of which is due to the extra processing inherent in them. I tried finding a few Dell 2407WFPs as well, but they are not to be found. Everything else is too expensive or has major issues like Input Lag. A superior H-IPS panel, especially at 26" and $700, not to mention the good reviews from just about everyone, and you have a winner that I couldn't refuse.

I also had a couple of 20" monitors previously with a resolution of 1680x1050. Doing some quick math tells you that the density of pixels is lower on the 20" vs. the 24", thus their size are larger. I can see the difference visually, as icons and such aren't as sharp and detailed as on the 24". I did the same calculation with the 26" vs. 24" and came to the same conclusion but just a bit less in ratio, naturally.

A 20" 1680x1050 monitor has 1,764,000 pixels with 88,200 pixels per inch of reference (I know I'm not calculating the exact area, but the comparison should still hold).

A 24" 1920x1200 monitor has 2,304,000 pixels with 96,000 pixels per inch of reference. So far so good, as we can see the 24" has a higher density of about 9%.

A 26" 1920x1200 monitor has 2,304,000 pixels with 88,615 pixels per inch of reference. Just ever so slightly higher than the 20" screen, which is good.

Following this wiki site:

http://en.wikipedia.org/wiki/Dot_pitch

Why is the pixel pitch higher, thus less detail and sharpness, on the 20" than the 24" when I very clearly remember the 24" having superior sharpness and detail? This brings me to wonder about the 26", when it has a similar ratio as the 24" compared to the 20". Also, this wiki-page states there are MORE pixel per inch on the 20" than the 24" or 26", which I know to be inaccurate. You don't get a sharper image on the 24" when you have less pixels...

I must be missing something in my analysis. Someone enlighten me please.

 

[AlNom]

y = Z/sqrt*3.56 (for 16:10); // vertical height of monitor

x=1.6*y; //horizontal length

pixels per inch = x.res/x = y.res/y

Z = 20.1" diagonal, 1680x1050

...

ppi = 98.56...


Z = 24" diagonal, 1920x1200

...

ppi = 94.33...


As for image quality, is it possible the 24" had better image processing/specs?

edit: Also keep in mind what Windows assumes for DPI in the display control panel.

oh and, your diagonal comparison does not hold because the slope of the line passing through the pixels does not guarantee accurate coverage of pixels along that path. You'd need a slope that covers each pixel equally - 0 or 45 degrees. Any other slope and the distance covered within each pixel will be different, producing an average ppi rather than a constant ppi.

 

[Berek]

y = Z/sqrt*3.56 (for 16:10); // vertical height of monitor

x=1.6*y; //horizontal length

pixels per inch = x.res/x = y.res/y

Z = 20.1" diagonal, 1680x1050

...

ppi = 98.56...


Z = 24" diagonal, 1920x1200

...

ppi = 94.33...


As for image quality, is it possible the 24" had better image processing/specs?

edit: Also keep in mind what Windows assumes for DPI in the display control panel.

oh and, your diagonal comparison does not hold because the slope of the line passing through the pixels does not guarantee accurate coverage of pixels along that path. You'd need a slope that covers each pixel equally - 0 or 45 degrees. Any other slope and the distance covered within each pixel will be different, producing an average ppi rather than a constant ppi.

Thank you, that makes much more sense. I was obviously oversimplifying my calculations as I thought they may apply. I was wondering why the density was different. This is good news though, as the quality of the 26" should be great then.

 

[EasyRaider]

Note that 26" is really 25.5", rounded up.

Pixel pitch (from memory)
20.1": 0.258 mm
24": 0.270 mm
25.5": 0.286 mm

As you can see, 26" monitors have poor definition compared to 20". But with enough space it's not really an issue, you can compensate by moving the monitor further away.

 

[Berek]

Note that 26" is really 25.5", rounded up.

Pixel pitch (from memory)
20.1": 0.258 mm
24": 0.270 mm
25.5": 0.286 mm

As you can see, 26" monitors have poor definition compared to 20". But with enough space it's not really an issue, you can compensate by moving the monitor further away.

Yeah, I've noticed this. It's unfortunate marketers don't always distinguish the difference.

It's still strange that I see a higher definition with the previous 24" I had. Even though apparently 20" are higher, I "feel" it differently, so I guess I'm not worried about the pixel pitch being .286, or .270.

What I need is screen real-estate first, combined with a large screen to spread out that real-estate. For example, I have a 17" WS 1920x1200 laptop. Great for the real-estate half, but it still hurts my eyes over-time due to the constrained size physically.

Dot pitch comes in as one of the last things for me, given my experience of seeing these larger monitors already. Just for fun, here is my priority list in order from most to least, not including price or warranty items as a factor:

1) Screen resolution (1920x1200 being ideal)

2) Screen physical size (24-27" being ideal)

3) Screen performance
a) excellent blacks and details
b) high color depth and accuracy
c) minimal back-light bleeding and distortions
d) low input lag
e) low response time
f) dot-pitch

4) Screen reliability
a) does not "age" fast in bulb light loss or otherwise
b) no dead/stuck pixels
c) sturdy enough to travel on occasion

5) General physical features
a) tilt
b) height
c) swivel
d) complete connectivity set (HDMI, etc.)
e) stylish base and bezel

 

[EasyRaider]

It doesn't make sense to consider dot pitch separately. By specifying area and number of pixels, area per pixel is also given.

Actually, I don't find it useful to think about physical pixel pitch at all. It's better to think in terms of pixels per degree (field of view), that's what matters to your eyes.

 

[Berek]

It doesn't make sense to consider dot pitch separately. By specifying area and number of pixels, area per pixel is also given.

Actually, I don't find it useful to think about physical pixel pitch at all. It's better to think in terms of pixels per degree (field of view), that's what matters to your eyes.

My thinking was along the lines of dotpitch = detail with all else being equal, but perhaps thats not quite the case.

One of the problems that fooled me was the larger icons and less definition I was seeing on 20.1" screens in comparison to 24". Someone mentioned earlier this was only the case due to the windows DPI setting being that way, and NOT the screen potential itself. If I had adjusted the DPI it would have completed changed my perspective. I no longer have those screens so I cannot test this.