Color Comparison of jetBook Color with Apple iPad 1 and Sony PRS-T1

[andyh2000]

I've put together a quick comparison of the same document (a page from a sample chapter of a technical book in PDF format) being displayed on a Sony PRS-T1, an Apple iPad 1 and the new Ectaco jetBook Color. You can find it here: http://jetbook-color-comparison.pen.io/ but the tl;dr version is shown below. For reference, the Sony is a 600x800 6" screen, the iPad 768x1024 9.7" and the jetBook Color a 600x800 colour, 1200x1600 black and white sub-pixels (it's complicated...) 9.7" screen.

Andrew

[tuxor]

The Jetbook looks pretty good to me... The iPad is a nice point of reference, but no real alternative to the two eink devices, as far as reading is concerned.

Thanks for the comparison. Maybe some information about the camera and the setting (background light etc.) would be good to know. Unfortunately, those pictures won't ever reflect real life experience with those screen technologies, even with extremely expensive equipment (camera etc.). But it's a good starting point for somebody, who doesn't have immediate access to those devices.

[X read X]

If these are all taken from the same distance the jetBook seems best, especially when looking at details like above the horizontal line in the 'e' and the diagonal lines in the 'W'

[andyh2000]

The pictures were taken with a Canon Powershot A480. Same distance, same zoom setting on the camera for each device, and the same lighting as much as was practical (one room light and a spotlight directly on the screens from about 4 inches off to one side, except for the iPad of course which gives off enough light on its own to flood a room...)

You haven't got a free zoom on the jetBook, you can only pick 50%, 75%, 80% etc. so I cropped the document using Briss to about what was showing on the other two devices.

You're right in that what the camera picks up isn't necessarily how your eyes see things. The jetBook screen is quite muddy (low contrast and dark) in comparison to the Sony PRS-T1 unless you have lots of light flooding on it (like I do in these shots). I expect it will look fantastic in full sunlight, but in a dim room at night it's a bit disappointing.

Andrew

[kamizase]

I am not sure if I understand, the Sony reader has the full page, A4 size, shown on a 6" screen, so it's effectively shrunk a bit more than two times, while the jetBook got the margins Brissed (almost 1.5" on each side), so the page fits almost 1:1? If yes, the no wonder the letters on the Sony look so thin, as antialiasing seems to kick in. You'd need to zoom in about twice on the Sony to give a better comparision.

Seperate issue is the yellowness of both screens. Maybe try putting a piece of white plain paper behind each ereader when taking a photo and use it to set white balance on the camera?

[wallcraft]

It looks like the jetBook is using the color pixels for anti-aliasing (or subpixel rendering at 800x600), and doing a good job of it.

We need is someone with jetBook and a USB microsope, see 400x magnification of Kindle screen. Note that 26x magnification is good enough.

[tuxor]

Originally Posted by kamizase

Seperate issue is the yellowness of both screens. Maybe try putting a piece of white plain paper behind each ereader when taking a photo and use it to set white balance on the camera?

That sounds like a good idea

[LeftyRight]

Thanks for the comparison Andrew.

cheers

LeftyRight

[ProDigit]

Looks like the Jetbook is using the interpolation between sub pixels. It also seems that the pixels are printed angled compared to the ipad where they are in a horizontal/vertical matrix.

I think they used part of the OLPC's research, in that they are using the same screen layout of pixels.
Very interesting indeed!
The negative side of having the pixels this way, is that no horizontal or vertical line will seem absolutely sharp, like they do show on the ipad's screen.

And since the alphabet consists mostly of horizontal and vertical lines (see the way characters in a text are written, and how many vertical lines each character has compared to how many diagonal lines), text might be looking sharper on the ipad.

The only edges of characters (letters) I can think of that might look sharp on the color are;
the left side of letter 'A',
top line of 'K' (perhaps),
Right middle line of 'M',
right and middle right sides of a 'V', and 'W',
and if you're lucky the'X', 'Y', and 'Z'.

While the Ipad will show many parts of the alphabet sharp (like the vertical lines in 'BDFHIJKLMNPRTY', and the horizontal lines in the characters 'AEFGHLPRTZ'); though not that it matters that much, as many parts of the characters also exist out of curves, and not only straights.

However, with subpixels, it seems that the jetbook is still capable of showing much smaller letters than the ipad.

[andyh2000]

Originally Posted by ProDigit

Looks like the Jetbook is using the interpolation between sub pixels.

I'm fairly sure it uses one sub-pixel at a time for black (leaving you potentially with a one sub-pixel wide colour fringe at the interface between a black and white area of an image).

Originally Posted by ProDigit

It also seems that the pixels are printed angled compared to the ipad where they are in a horizontal/vertical matrix.
...

I think what you're seeing is a checkerboard pattern where two of the RGBW sub-pixels are more visible than the others in the "white" background areas. For instance if they're arranged like this:

RG|RG|RG
BW|BW|BW
--------
RG|RG|RG
BW|BW|BW

The blue and green might be most visible, so it would look like this:

 G| G| G
B |B |B 
--------
 G| G| G
B |B |B

At least that's what I think is going on. Good as my camera is for a point and shoot I still haven't quite resolved the sub-pixels properly yet. I need to try a super macro close up, but then lighting gets difficult.

Edited: Found a diagram here: http://www.eetimes.com/electronics-n...s-color-ePaper

If this is the final layout of the Triton film then I'd guess we really are seeing the Blue and Green sub-pixels.



I'm now itching to buy a cheap USB microscope...

Andrew

[andyh2000]

Originally Posted by kamizase

I am not sure if I understand, the Sony reader has the full page, A4 size, shown on a 6" screen, so it's effectively shrunk a bit more than two times, while the jetBook got the margins Brissed (almost 1.5" on each side), so the page fits almost 1:1? If yes, the no wonder the letters on the Sony look so thin, as antialiasing seems to kick in. You'd need to zoom in about twice on the Sony to give a better comparision.

I was really comparing the jetBook with the iPad to see if it could render the PDF better when displaying all the text (as Ectaco claim it can with the 1200x1600 sub-pixel resolution). I threw in the PRS-T1 as that has a 600x800 screen which is what some people were expecting the jetBook would look like. Clearly it's better than that, and in my opinion much better than the iPad too so Ectaco weren't exaggerating (or at least not much).

Andrew

[kamizase]

Originally Posted by andyh2000

I threw in the PRS-T1 as that has a 600x800 screen which is what some people were expecting the jetBook would look like. Clearly it's better than that,

Clearly bigger looks better. And no jetBook wouldnt look the same as the sony, because it is bigger! The 6" e ink screen is 167dpi, while the jetBook starts with 200dpi and the colour filter layer reduces that to 100dpi. That means a dot on the JB is 1.67x1.67= 2.79 times bigger than on a 6" ereader. And you further skewed it in favour of the jetBook by removing margins from the tested pdf file. To make up for the difference, you need to zoom in on the Sony, at least 167% size , or zoom out on the JetBook, at least to 60% size if not lower. Having a sample of text of equal physical size (you can take a ruller and measure if they are the same ) will allow meaningful comparisions. Because it is no suprise to anyone who tried to fit an A4 size page on a 6" ebook reader, that this looks bad and is very hard to read. Hence the interest in bigger ereaders.

That being said, the jetbook has actualy three ways on generating a "black" pixel by a combination of subpixels: (W = the nonfiltered subpixel being turned on, so being actualy black)

|RG| |RG| | |
|BW| |B | | W|

Having the pixels in diagonal would actualy help rendering the letters with diagonal lines. Maybe even horizontal ones. Let's see if ASCII art works:

/ R \W/R \W/R\W/R \W/R\W/R \
|G B||G B||G B||G B||G B||G B|
\ W/R \W/R\W/R \W/R \W/R\W/R \
B||G B||G B||G B||G B||G B||G B|

Yay, a non-jagged horizontal line!

[andyh2000]

Originally Posted by kamizase

Clearly bigger looks better. And no jetBook wouldnt look the same as the sony, because it is bigger! The 6" e ink screen is 167dpi, while the jetBook starts with 200dpi and the colour filter layer reduces that to 100dpi. That means a dot on the JB is 1.67x1.67= 2.79 times bigger than on a 6" ereader. And you further skewed it in favour of the jetBook by removing margins from the tested pdf file. To make up for the difference, you need to zoom in on the Sony, at least 167% size , or zoom out on the JetBook, at least to 60% size if not lower. Having a sample of text of equal physical size (you can take a ruller and measure if they are the same ) will allow meaningful comparisions. Because it is no suprise to anyone who tried to fit an A4 size page on a 6" ebook reader, that this looks bad and is very hard to read. Hence the interest in bigger ereaders.

That being said, the jetbook has actualy three ways on generating a "black" pixel by a combination of subpixels: (W = the nonfiltered subpixel being turned on, so being actualy black)

|RG| |RG| | |
|BW| |B | | W|

Having the pixels in diagonal would actualy help rendering the letters with diagonal lines. Maybe even horizontal ones. Let's see if ASCII art works:

/ R \W/R \W/R\W/R \W/R\W/R \
|G B||G B||G B||G B||G B||G B|
\ W/R \W/R\W/R \W/R \W/R\W/R \
B||G B||G B||G B||G B||G B||G B|

Yay, a non-jagged horizontal line!

As I said, I was really comparing the iPad with the jetBook but threw in the Sony as some people were claiming the jetBook would look like it had a resolution of 600x800 even in black and white. If it did then displaying the PDF page would look as pixelated on it as on the Sony (by the way, I forgot to mention I used the margin cut mode on the Sony), albeit with pixels that are physically bigger. Obviously that's not the case, so I established to my satisfaction it could render b&w text at a higher resolution than that. Then I compared it with the iPad (which is the same physical size), and again I'm satisfied that the jetBook can render at a higher resolution than 768x1024.

It's a separate issue what something looks like on both screens at the same physical size, but since you're so interested here you are. I made the text the same physical size on the Sony and the jetBook (or as close as I could), and kept the camera distance and zoom setting the same. Click to zoom in.





Why I bought the jetBook is to read a PDF a page at a time without having to zoom in. And it looks like I'm able to do that, although I might still have to margin cut some documents.

Andrew

PS I suspect you're wrong about the sub-pixel rendering when it's pure black text on a pure white background (in the source document that is) but I have no way of testing it (yet).

[mod186k1]

May be Italian is not your language, but if you are interested in Jetbook Color screen technology (e-ink triton) you can see an very interesting analysis on:

http://forum.simplicissimus.it/altro...-microspcopio/


AM

[andyh2000]

Originally Posted by mod186k1

May be Italian is not your language, but if you are interested in Jetbook Color screen technology (e-ink triton) you can see an very interesting analysis on:

http://forum.simplicissimus.it/altro...-microspcopio/


AM

Thanks for that - very interesting. Looks like it's the red/blue pixels we can see (with the naked eye as well) and they're staggered row to row (to avoid Moiré patterns it says).

I've just hit the "Buy" button on a USB microscope from Amazon, so I should be able to do something similar as from tomorrow (Wednesday) night.

Andrew