Touch What's the exact pixel resolution of Kobo Touch?

keijemon · 10-08-2011, 07:46 PM

When I first looked at Kobo a year ago, I have found this thread regarding the original Kobo:
https://www.mobileread.com/forums/showthread.php?t=87110

People there figured out the exact pixel screen resolution of the original Kobo (not the advertized 800x600 total resolution, but the real usable pixel area, which turned out to be 540x718). I was wondering if anyone has done similar investigation with the Touch variety? I cannot find anything on the subject.

My intent is to resize images on PC side using batch processing in Photoshop, with its superior resizers and filters, and to avoid Kobo doing any touch ups, so I need to know the resolution I should target.

Thanks.

The Terminator · 10-08-2011, 09:35 PM

I'm not sure.

keijemon · 10-09-2011, 10:15 AM

Where in the source will I be able to look up these values?

kanex · 10-09-2011, 12:54 PM

It's 600*800 for kobo touch. I prepares such CBZ and they works perfectly.

keijemon · 10-09-2011, 02:35 PM

Quote:

Originally Posted by kanex

It's 600*800 for kobo touch. I prepares such CBZ and they works perfectly.

All cbz work, I've tried some with double the resolution and they've worked. That's not the point, the point is that the resizer Kobo uses is lacking in quality, so I want to know the exact resolution of the screen so I can use a better resizer on the desktop and prevent the one on Kobo from kicking-in.

larrymohr · 10-11-2011, 03:39 PM

I think you will find that whatever you do to "preprocess" the cover, the Kobo firmware will still process the image. The cover images are dithered to grayscale even if you have a grayscale cover image. They are also resized in some as yet unknown fashion. I have tried several methods of creating covers and have yet to discover a way to get the exact cover I want except by copying the file directly to the thumbnail directory on the Kobo.

Note that I have not done any experimenting since version 1.9.9 or 1.9.10 so there may have been changes.

kanex · 10-12-2011, 12:40 AM

Quote:

Originally Posted by keijemon

All cbz work, I've tried some with double the resolution and they've worked. That's not the point, the point is that the resizer Kobo uses is lacking in quality, so I want to know the exact resolution of the screen so I can use a better resizer on the desktop and prevent the one on Kobo from kicking-in.

By perfectly... I mean not resizing. 100% pixel-to-pixel display.

Nigol · 10-13-2011, 09:29 AM

Some changes have been done in firmware 1.9.10, but there is still issues. What you need to remember is that when the Kobo process the cover it also takes into account the formatting of the page like margins etc. So that means that even if you have your cover at exactly 600 X 800 if things like margins will come into account.

So like it was said, the Kobo will process the file either way because it is not just the image but the whole html file that matters. Also the kobo creates 4 different thumbnails for each cover dimensions, so it will process them either way. Try using really high resolution image seems to render a better image quality. (so cover of 300 X 400 will never look good on them, search google images for example and you can find some really high res images).

Also if interested look at my app in my sig, it has a cover editor that will automate the process and create the html so that everything fits without borders, and you could easily change your images with it.

MacEachaidh · 02-12-2012, 03:27 AM

I know this is marked as an old thread, but it seems to be essentially unanswered, so I wonder if anyone has anything to add? I've searched, but I can't find the actual specs either. I know the screen is stated as being 600 x 800 pixels, but some of the screen is hidden by the housing, isn't it?

So, does anyone know:
What's the actual specific resolution of the visible part of the display?

notzed · 02-13-2012, 10:21 PM

It's 800x600 exactly. I know this as i've written code to write directly to the framebuffer device, and that's how big it is. All 800x600 pixels are visible on mine.

However, the pixels right near the edge are hard to read even if they are not obscured by a mis-aligned bezel, mostly because of shadows or the angle of view: so software needs to add a border for usability, I don't know what border the kobo software is adding for title pages.

I've been reading text files and one gets a lovely blank title page everywhere they might show up - how so very useful ...

AFAIK the kobo uses a 16-bit RGB 565 mode for the display screen, so perhaps a 4 or 6 bit greyscale png would go through unchanged but that's only a guess. It's an odd choice and probably because they want to use the same code on different devices or maybe to simplify client-side dithering. The hardware itself (or driver) supports an 8-bit greyscale mode, although displays in only 16 shades.

murg · 02-15-2012, 07:37 AM

The screen appears to be 600x800.

I tried to use 4 bit greyscale pngs, what with the screen being 16 greyscale levels and all, but they turned out horrible.

Full 24 bit colour jpgs seem to work the best. I resize all of my images to fit the Kobo Touch screen without it having to do the resizing.

trevorburdon · 03-03-2013, 06:46 AM

These similar topice do seem to go around and around don't they.

So keijemon can take it that the visible screen is 600*800. That's great for covers, but how much is it reduced for a kobo paeg with standard margiins?

I think an answer to this question would fill in the reply to him and be generally useful to everyone else who wonders like I do!

MacEachaidh · 03-03-2013, 03:33 PM

I established by my own tests, and had it confirmed by Kobo tech support, that the screen on the Kobo Touch is 600x800 pixels @ 167 ppi.

Nowadays I usually edit the eBook and set the cover to that size and ratio, and find it gives a good result. Since colour covers are often less clear on a monochrome device, I generally convert them to greyscale and shift tones to raise the contrast as well.

TechniSol · 03-05-2013, 12:29 AM

OTOH, it wouldn't hurt if Kobo gave us a choice of tweaking at least the midpoint of the curve when it converts covers to grayscale. Even just the ability to go in and tweak a cover after the fact would be great.

Wouldn't mind a similar ability to tweak the display or just plain remap when trying to use the browser too.

MacEachaidh · 03-05-2013, 12:38 AM

Yes, TechniSol, I agree. There are other things I wish Kobo would do as well — such as some sort of developer's guide to optimising the formatting of books for Kobo's own reader software quirks. (Though that might only encourage Kobo to go too far in a proprietary direction. It's better that it be restrained from not straying too far from standard codes.)

But I suspect those of us who care about spending time on such things are in the fairly extreme majority. Most users just expect to be able to download a book from the vendor and for it to simply work. I doubt enough people are interested in customising such things as covers for Kobo to bother spending any development time on it.

10-08-2011, 07:46 PM	#1
keijemon Junior Member Posts: 6 Karma: 10 Join Date: Oct 2011 Device: kobo ereader touch	What's the exact pixel resolution of Kobo Touch? When I first looked at Kobo a year ago, I have found this thread regarding the original Kobo: https://www.mobileread.com/forums/showthread.php?t=87110 People there figured out the exact pixel screen resolution of the original Kobo (not the advertized 800x600 total resolution, but the real usable pixel area, which turned out to be 540x718). I was wondering if anyone has done similar investigation with the Touch variety? I cannot find anything on the subject. My intent is to resize images on PC side using batch processing in Photoshop, with its superior resizers and filters, and to avoid Kobo doing any touch ups, so I need to know the resolution I should target. Thanks.

10-08-2011, 09:35 PM	#2
The Terminator Retired Posts: 2,552 Karma: 37638420 Join Date: Nov 2010 Location: Vancouver Island Canada Device: Kobo Touch, Optimus One (2.3), Nexus 7 (4.2)	I'm not sure. Last edited by The Terminator; 02-14-2012 at 12:40 PM.

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10-09-2011, 10:15 AM	#3
keijemon Junior Member Posts: 6 Karma: 10 Join Date: Oct 2011 Device: kobo ereader touch	Where in the source will I be able to look up these values?

10-09-2011, 12:54 PM	#4
kanex Junior Member Posts: 7 Karma: 3536 Join Date: Aug 2011 Device: Kobo Touch	It's 600*800 for kobo touch. I prepares such CBZ and they works perfectly.

10-11-2011, 03:39 PM	#6
larrymohr Zealot Posts: 104 Karma: 29873 Join Date: Jul 2010 Location: Surrey, B.C. Device: Kobo Libra Color, Kobo Sage, AURA One, Mini	I think you will find that whatever you do to "preprocess" the cover, the Kobo firmware will still process the image. The cover images are dithered to grayscale even if you have a grayscale cover image. They are also resized in some as yet unknown fashion. I have tried several methods of creating covers and have yet to discover a way to get the exact cover I want except by copying the file directly to the thumbnail directory on the Kobo. Note that I have not done any experimenting since version 1.9.9 or 1.9.10 so there may have been changes.

10-13-2011, 09:29 AM	#8
Nigol Groupie Posts: 185 Karma: 363616 Join Date: Dec 2010 Location: Montreal, Canada Device: Kobo Original, Kobo Touch	Some changes have been done in firmware 1.9.10, but there is still issues. What you need to remember is that when the Kobo process the cover it also takes into account the formatting of the page like margins etc. So that means that even if you have your cover at exactly 600 X 800 if things like margins will come into account. So like it was said, the Kobo will process the file either way because it is not just the image but the whole html file that matters. Also the kobo creates 4 different thumbnails for each cover dimensions, so it will process them either way. Try using really high resolution image seems to render a better image quality. (so cover of 300 X 400 will never look good on them, search google images for example and you can find some really high res images). Also if interested look at my app in my sig, it has a cover editor that will automate the process and create the html so that everything fits without borders, and you could easily change your images with it.

02-12-2012, 03:27 AM	#9
MacEachaidh Browser Posts: 745 Karma: 578294 Join Date: Apr 2010 Location: Australia Device: Kobo Touch, Kobo Aura HD	I know this is marked as an old thread, but it seems to be essentially unanswered, so I wonder if anyone has anything to add? I've searched, but I can't find the actual specs either. I know the screen is stated as being 600 x 800 pixels, but some of the screen is hidden by the housing, isn't it? So, does anyone know: What's the actual specific resolution of the visible part of the display?

02-13-2012, 10:21 PM	#10
notzed Member Posts: 15 Karma: 400 Join Date: Jan 2012 Device: kobo touch	It's 800x600 exactly. I know this as i've written code to write directly to the framebuffer device, and that's how big it is. All 800x600 pixels are visible on mine. However, the pixels right near the edge are hard to read even if they are not obscured by a mis-aligned bezel, mostly because of shadows or the angle of view: so software needs to add a border for usability, I don't know what border the kobo software is adding for title pages. I've been reading text files and one gets a lovely blank title page everywhere they might show up - how so very useful ... AFAIK the kobo uses a 16-bit RGB 565 mode for the display screen, so perhaps a 4 or 6 bit greyscale png would go through unchanged but that's only a guess. It's an odd choice and probably because they want to use the same code on different devices or maybe to simplify client-side dithering. The hardware itself (or driver) supports an 8-bit greyscale mode, although displays in only 16 shades.

02-15-2012, 07:37 AM	#11
murg No Comment Posts: 3,240 Karma: 23878043 Join Date: Jan 2012 Location: Australia Device: Kobo: Not just an eReader, it's an adventure!	The screen appears to be 600x800. I tried to use 4 bit greyscale pngs, what with the screen being 16 greyscale levels and all, but they turned out horrible. Full 24 bit colour jpgs seem to work the best. I resize all of my images to fit the Kobo Touch screen without it having to do the resizing.

03-03-2013, 06:46 AM	#12
trevorburdon Junior Member Posts: 9 Karma: 10 Join Date: May 2012 Location: Melbourne Device: none	These similar topice do seem to go around and around don't they. So keijemon can take it that the visible screen is 600*800. That's great for covers, but how much is it reduced for a kobo paeg with standard margiins? I think an answer to this question would fill in the reply to him and be generally useful to everyone else who wonders like I do!

03-03-2013, 03:33 PM	#13
MacEachaidh Browser Posts: 745 Karma: 578294 Join Date: Apr 2010 Location: Australia Device: Kobo Touch, Kobo Aura HD	I established by my own tests, and had it confirmed by Kobo tech support, that the screen on the Kobo Touch is 600x800 pixels @ 167 ppi. Nowadays I usually edit the eBook and set the cover to that size and ratio, and find it gives a good result. Since colour covers are often less clear on a monochrome device, I generally convert them to greyscale and shift tones to raise the contrast as well.

03-05-2013, 12:29 AM	#14
TechniSol GranPohbah-Fezzes r cool! Posts: 1,056 Karma: 3151024 Join Date: Jul 2010 Device: Nook STRs, Kobo Touch, Kobo Glo	OTOH, it wouldn't hurt if Kobo gave us a choice of tweaking at least the midpoint of the curve when it converts covers to grayscale. Even just the ability to go in and tweak a cover after the fact would be great. Wouldn't mind a similar ability to tweak the display or just plain remap when trying to use the browser too.

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03-05-2013, 12:38 AM	#15
MacEachaidh Browser Posts: 745 Karma: 578294 Join Date: Apr 2010 Location: Australia Device: Kobo Touch, Kobo Aura HD	Yes, TechniSol, I agree. There are other things I wish Kobo would do as well — such as some sort of developer's guide to optimising the formatting of books for Kobo's own reader software quirks. (Though that might only encourage Kobo to go too far in a proprietary direction. It's better that it be restrained from not straying too far from standard codes.) But I suspect those of us who care about spending time on such things are in the fairly extreme majority. Most users just expect to be able to download a book from the vendor and for it to simply work. I doubt enough people are interested in customising such things as covers for Kobo to bother spending any development time on it.