Discussion in 'Digital Darkroom' started by joe_c|5, Nov 21, 2010.

1. ### joe_c|5

Hello, I will not argue here and ask others not to either, but rather I am looking for an answer to a simple question that is relevant to one of the strangest arguments I have ever seen.
In the attached image, does the larger pattern at the top look like smaller pattern A, smaller pattern B, or neither one?

2. ### vincent_peri

Going purely on my first impression, I'd say that the top diagram looks like the bottom half of diagram A and the top half of diagram B. I see a capital "H" in the top one, but I don't see the "H" in either A or B.
So for me, the answer is neither.

3. ### mukul_dube

Top diagram is three colours, not two colours like A and B.
B is immediately the better match. A would have to be reversed, in both senses.
Do you propose to not tell us what is the argument?

4. ### CoryAmmerman

It looks more like "B" except that "B" doesn't have the thin horizontal lines on the left and right like the top image does. At least that's what it looks like on my monitor.

5. ### joe_c|5

The argument starts a few pages into the thread at http://www.photo.net/digital-darkroom-forum/00Xgse if you are that interested. The topic is primarily resizing images.

To me the top one looks like a combination of both dark and light squares, but it one has the little horizontal lines on either side.

7. ### mark_sirota|1

It doesn't look like either one -- the top one has alternating black and white stripes on the sides; the bottom two have different shades of gray.
It is interesting to me that it looks closer to B than A. It should look more like A, because the darker grey is closer to middle grey, which is what I'd expect from the alternating black and white stripes.

8. ### joe_c|5

The darker gray is meant to be around 21% gray and the lighter gray is meant to be around 50% gray, though the exact colors may vary with the monitor.

9. ### joseph_wisniewski

With my monitor and calibration, B.
But there's no way to settle your argument. A resizing algorithm that "prefilters" will look like B. A resizing algorithm that doesn't will look randomly like A, B, or some weird hybrid.

10. ### joe_c|5

The argument is about what they should look like, not what they do look like.

11. ### francisco_disilvestro

It should look like B

12. ### chrisnielsen

I can tilt my LCD up and down and it switches between A and B.

13. ### michael_young|3

The question, of course, is to gamma. If I scrunch down to desktop level and squint and cross my eyes so the stripes blend, they almost blend to look closer to B. Copying and pasting into PS, and zooming out to 50%, so the stripes actually do blend, it looks like A. My monitors were calibrated within the week with an i1Display2. I don't recall the gamma selected.

14. ### mike dixon

The argument is about what they should look like, not what they do look like.
If that's the case, it's pointless to ask people what they look like. You're not settling anything--you're just dragging the argument into another thread.

15. ### JeffOwen

To me , neither. Even if I screw my eyes so I don't see the grid pattern the edges appear mid way between the two greys.

16. ### StuartMoxham

Well if I squint my eyes the big one looks like B.

17. ### mark_sirota|1

I wrote:
It doesn't look like either one -- the top one has alternating black and white stripes on the sides; the bottom two have different shades of gray.
It is interesting to me that it looks closer to B than A. It should look more like A, because the darker grey is closer to middle grey, which is what I'd expect from the alternating black and white stripes.​
I wonder whether it would look more like A if it were on black instead of white. (I realize this is a different question than the gamma question in the other thread; here I've moved on to human visual perception.)

18. ### Dieter Schaefer

On both my monitors it looks more like B - both are calibrated with Colorvision Spyder with a Gamma of 2.2. At 50% zoom level in photoshop (or after zooming out 4x in firefox) the pattern changes to A.

19. ### vel_ziliuse

To me the diagram on top looks like an "H", the A diagram looks like an "A" and the B diagram looks like an "U". But if I had to chose one I would go for the A. Because the sidebands of the top diagram, to me, look darker than its bottom half.

20. ### digitaldog

Which version here looks correct?
Squint, rotate the display, look at the preview from across any sized room. And keep in mind, if one is right, the other are therefore wrong.
Note they are identical, just zoomed differently in Photoshop.

21. ### mark_sirota|1

Good idea, looking at the image from across the room. It clearly looks more like B. Almost exactly like B.
Can someone please explain why that is? If it is explained in the other thread, I can't find it -- too many tangents to follow.

22. ### Tim_Lookingbill

Joe, on my EyeOne Display calibrated 2004 G5 iMac viewed in color managed Safari, "B" looks like the top center larger version except the stripes are a solid gray and blend as one U-shaped solid gray with the bottom square on "B".
I don't know how you can derive anything from this viewing on an 8 bit video system. I wonder also if LCD panel and phasing technology can influence the downsampled appearance differences considering all the different answers you've been getting.
I remember the rise and fall pixel timing issues with CRT's as the argument against using eyeball calibrators that relied on raster line blending targets and as a determiner of actual gamma.

23. ### gkgerber

Okay... When I first looked at it, I though it doesn't look like either, it looks like a dark grey square over a light grey square with black and white striped lines on either side. However, when I look at it from a high angle toward the monitor it looks like A and from a low angle it looks like B.

24. ### model mayhem gallery

A and B are invereses both being one half of the whole. If you merge A and B and interleave the parts that over lap you will get the center image. It's like asking which is correct in the Ying Yang symbol, the white part or the black part?

25. ### model mayhem gallery

A and B are invereses both being one half of the whole. If you merge A and B and interleave the parts that over lap you will get the center image. It's like asking which is correct in the Ying Yang symbol, the white part or the black part?

26. ### joe_c|5

Good idea, looking at the image from across the room. It clearly looks more like B. Almost exactly like B.
Can someone please explain why that is? If it is explained in the other thread, I can't find it -- too many tangents to follow.​
The alternating black and white lines on most monitors emit around 50% as much light as solid white would. The lighter gray color on most monitors emits around 50% as much light as solid white would. The darker gray color on most monitors emits around 21% as much light that solid white would. The lines therefore look similar to the lighter color if viewed from far away.
Many monitors do not exactly match sRGB and are not profiled. In this case the image might only look somewhat like B instead of exactly like B.

27. ### digitaldog

Many monitors do not exactly match sRGB and are not profiled​
Boy ain’t that the true when you consider the actual specifications for sRGB (a P22 phosphor for one). If anyone is matching the exact sRGB spec (which is based upon a theoretical display) in 2010, its a very old display indeed!

28. ### mark_sirota|1

Joe, thanks for the concise explanation. I was misled by thinking that grey level was analogous to light level.

29. ### Uhooru

My lab rat is on a coffee and smoke break at the moment, but I'll get em right on when he returns..

30. ### joe_c|5

I remember the rise and fall pixel timing issues with CRT's as the argument against using eyeball calibrators that relied on raster line blending targets and as a determiner of actual gamma.​
I think it is at least reasonable if the light and dark lines are on separate CRT scan lines. It was when vertical lines or cross hatch patterns were used on a CRT that the pixel rise and fall times tended to cause large errors.

31. ### StuartMoxham

I still use my CRT monitor and still have a CRT TV. I like them.

32. ### mauro_franic

The top looks like an image taken with film. (B) looks like an image of the same/similar subject taken with a digital camera where all the fine details merge together.

33. ### joseph_wisniewski

What is it about this site, that no matter what somebody says, someone comes along and turns it into a reason for some "digital bashing".
Bob: Dang, it's hot out today...
Sam: Yeah, those digital cameras are causing global warming. It never got this hot back when people shot more film.

34. ### mauro_franic

just a light hearted joke.

35. ### StuartMoxham

Thats funny Mauro.

36. ### rodeo_joe|1

Why not just ask if anyone is using a linear Gamma or 2.2?
Nobody in their right mind or with a normal set of eyeballs will be using unity gamma (top match), and in any case the 2.2 gamma mid-grey value should be 186, not 187. Also, the jpeg file format carries colour space information which may alter how it appears on other people's monitors. So if you're going to try this experiment, then you need to use a non-corrupting and space-independent indexed file format like GIF.
Further, if not viewed at 100% the horizontal bars won't display 50% brightness, and on most LCD monitors the perceived gamma varies wildly with the viewers eyeline.
BTW, my answer is - "neither". I have my monitor set to a calibrated gamma of 1.8.

37. ### greg_kowalczewski

Neither! So I guess my eye sight is pretty good.

38. ### 15sunrises

Sitting a bit further back it clearly looks more like B.

39. ### joe_c|5

in any case the 2.2 gamma mid-grey value should be 186, not 187. Also, the jpeg file format carries colour space information which may alter how it appears on other people's monitors.​
Both of these were deliberate, the value of 187 since the tone curve is sRGB instead of gamma 2.2 (they are slightly different) and the color space information since it may improve accuracy with a profiled monitor.

40. ### Kent Shafer

…and on most LCD monitors the perceived gamma varies wildly with the viewers eyeline.​
That's the main thing I've learned from this thread so far. To make the top image look like B, I have now raised my monitor a couple of inches by putting a book under it. (A book of poetry since it's about the right thickness and I don't care much for poetry anyway.)
My monitor is a garden variety HP (HP w22). Would one of the oft-recommended NEC monitors fare better in this regard? I'm looking for an excuse to get one.

41. ### digitaldog

Would one of the oft-recommended NEC monitors fare better in this regard? I'm looking for an excuse to get one.​
No, I have two and this example is in no way much useful let alone any indication of display quality. But yes, you should consider getting a SpectraView for much better reasons than what the items above look like!