No Header keep footer - Image size

[Griu]

Hi,

I've got a kobo Glo HD. I've been looking arounf but I haven't been able to find a solution for this.

1- Is there a way to remove the header on kepubs but keeping the footer? I don't want to convert the files to epuv since I'll lose some functions.

2- I know the ppi is really high on this device, but I prevously owned a kindle paperwhite 2015 with the same ppi and the images showed up fine. The problem is guess this has something to do with the resolution but they were showing up fine on the kindle. Any way to fix this?


If there are other posts about this I haven't found them.

[JSWolf]

Originally Posted by Griu

Hi,

I've got a kobo Glo HD. I've been looking arounf but I haven't been able to find a solution for this.

1- Is there a way to remove the header on kepubs but keeping the footer? I don't want to convert the files to epuv since I'll lose some functions.

2- I know the ppi is really high on this device, but I prevously owned a kindle paperwhite 2015 with the same ppi and the images showed up fine. The problem is guess this has something to do with the resolution but they were showing up fine on the kindle. Any way to fix this?


If there are other posts about this I haven't found them.

I cannot answer #1, but as for #2, it depends on the books and the resolution of the images. A lot of eBooks have quite low resolution images that do not show up well on a hi-resolution screen such as on the Glo HD.

[Griu]

Originally Posted by JSWolf

I cannot answer #1, but as for #2, it depends on the books and the resolution of the images. A lot of eBooks have quite low resolution images that do not show up well on a hi-resolution screen such as on the Glo HD.

Thanks for replying. The thing is the kindle paperwhite has the same screen resolution and images are not that small. I opened one using Google play books on a tablet an they aren't that small either. I'm guessing is a setting on the kobo reader but I don't know if it can be modified.

[GeoffR]

Originally Posted by Griu

1- Is there a way to remove the header on kepubs but keeping the footer? I don't want to convert the files to epuv since I'll lose some functions.

Up to and including firmware version 3.18.0 there was a showPageHeader=false entry you could add to the device's configuration file that would remove the title text from the top of the page in KePubs, but it still left a blank area where the text was.

But this no longer works in the current firmware, and there is no other way I know to remove the KePub header without removing the footer too.

Originally Posted by Griu

2- I know the ppi is really high on this device, but I prevously owned a kindle paperwhite 2015 with the same ppi and the images showed up fine. The problem is guess this has something to do with the resolution but they were showing up fine on the kindle. Any way to fix this?

One thing to check if you are using Calibre to convert the books is that you have Preferences > Common options > Output profile set to Tablet. If you have it set to something else the size of the images will be reduced when the book is converted.

Apart from that, it is up to the publisher to set the size of the image in the book. If the publisher doesn't specify a size then the image is displayed at its natural pixel size. Unfortunately many publishers either don't bother to specify a size, or else specify an absolute or pixel size that will only look right on devices with a certain screen resolution.

(The strange thing is that some publishers do the cover image correctly, proving that they know how to size the images relative to screen size, but then fail to do the same for the other images in the book.)

What the publisher should do is specify the image size relative to the screen size of the device it is being displayed on (by using height:90%; for example), or in some cases relative to the font size the reader has selected (using height:2em; for example.) If this is the problem then all you can do is edit the book before sideloading. There are two approaches to editing the image sizes for the book:


1. Use image manipulation tools such as ImageMagick to resize all the images in the book to suit your device. This works for those cases where the publisher has not specified a size for the images in the CSS/HTML. e.g. if the publisher has made the images sized to suit a 600x800 screen, then resizing with a scale factor of 180% should make them the right size for a 1080x1440 device. This can often be done with a single command (mogrify -resize 180% *.jpg).

The advantage of this approach is that it is easier for books where there are a large number of images, and it doesn't require any knowledge of CSS/HTML. The disadvantage is that it will have to be re-done when you want to load the book to another device with a different size screen, and it might not work if the publisher has specified an absolute or pixel size in the CSS/HTML.


2. Edit the CSS and/or HTML files to specify the image size relative to the screen size. E.g. if the image is 400x700 pixels and the images are suitable for a 600x800 device then you could set the size as height:87.5%; width:auto; and the image would have the same size relative to the screen height on all devices. (You might also want to look at using min-height,max-height,min-width,max-width styles, or look into using a SVG block if you want finer control of things such as aspect ratios.)

The Advantage of this approach is that it will work for devices with different screen sizes -- it is what the publisher should have done in the first place. The disadvantage is that you will probably need to edit each HTML entry for each image separately -- a lot of work if there are a lot of images -- and know enought about CSS/HTML to know what to edit.

In both cases the quality of the results will be limited by the quality of the original images provided by the publisher.

[Griu]

Originally Posted by GeoffR

Up to and including firmware version 3.18.0 there was a showPageHeader=false entry you could add to the device's configuration file that would remove the title text from the top of the page in KePubs, but it still left a blank area where the text was.

But this no longer works in the current firmware, and there is no other way I know to remove the KePub header without removing the footer too.




One thing to check if you are using Calibre to convert the books is that you have Preferences > Common options > Output profile set to Tablet. If you have it set to something else the size of the images will be reduced when the book is converted.

Apart from that, it is up to the publisher to set the size of the image in the book. If the publisher doesn't specify a size then the image is displayed at its natural pixel size. Unfortunately many publishers either don't bother to specify a size, or else specify an absolute or pixel size that will only look right on devices with a certain screen resolution.

(The strange thing is that some publishers do the cover image correctly, proving that they know how to size the images relative to screen size, but then fail to do the same for the other images in the book.)

What the publisher should do is specify the image size relative to the screen size of the device it is being displayed on (by using height:90%; for example), or in some cases relative to the font size the reader has selected (using height:2em; for example.) If this is the problem then all you can do is edit the book before sideloading. There are two approaches to editing the image sizes for the book:


1. Use image manipulation tools such as ImageMagick to resize all the images in the book to suit your device. This works for those cases where the publisher has not specified a size for the images in the CSS/HTML. e.g. if the publisher has made the images sized to suit a 600x800 screen, then resizing with a scale factor of 180% should make them the right size for a 1080x1440 device. This can often be done with a single command (mogrify -resize 180% *.jpg).

The advantage of this approach is that it is easier for books where there are a large number of images, and it doesn't require any knowledge of CSS/HTML. The disadvantage is that it will have to be re-done when you want to load the book to another device with a different size screen, and it might not work if the publisher has specified an absolute or pixel size in the CSS/HTML.


2. Edit the CSS and/or HTML files to specify the image size relative to the screen size. E.g. if the image is 400x700 pixels and the images are suitable for a 600x800 device then you could set the size as height:87.5%; width:auto; and the image would have the same size relative to the screen height on all devices. (You might also want to look at using min-height,max-height,min-width,max-width styles, or look into using a SVG block if you want finer control of things such as aspect ratios.)

The Advantage of this approach is that it will work for devices with different screen sizes -- it is what the publisher should have done in the first place. The disadvantage is that you will probably need to edit each HTML entry for each image separately -- a lot of work if there are a lot of images -- and know enought about CSS/HTML to know what to edit.

In both cases the quality of the results will be limited by the quality of the original images provided by the publisher.

Thanks. I used calibre and tried many output profiles. All with the same result. But my question now would be, why do I see the images the right way using an ebook reader on android or when I sideload them to the paperwhite 3? If the book isn't properly set up, shouldn't I see the wrong size on all devices? It looks like it's the way kobo shows the book that's the problem.

Oh, btw. This happens with all my books. I remember Google play books used to behave this way until the updated it, many months ago, and now it shows up fine. That's why I think it's a reader problem and not a book problem.

[GeoffR]

Originally Posted by Griu

Thanks. I used calibre and tried many output profiles. All with the same result. But my question now would be, why do I see the images the right way using an ebook reader on android or when I sideload them to the paperwhite 3? If the book isn't properly set up, shouldn't I see the wrong size on all devices? It looks like it's the way kobo shows the book that's the problem.

Oh, btw. This happens with all my books. I remember Google play books used to behave this way until the updated it, many months ago, and now it shows up fine. That's why I think it's a reader problem and not a book problem.

It might be that other devices are overriding the size specified by the publisher. The problem with that is there is no way for an algorithm to know for sure what size the publisher intended, it requires some human judgement. Should it be relative to the screen size or to the font size? Did the publisher intend to have images 100% of screen height but only tested on a 600x800 screen, or did they intend 80% but only tested on a 758x1024 screen? Any automatic resizing algorithm is going to make some mistakes.

I think this is the same issue for a lot of other aspects of ebook display: does the device override the publisher's settings, which make books by bad publishers look better and books by good publishers look worse, or do they respect the publisher's settings so that books by bad publishers will look bad and books by good publishers will look good?

[Griu]

Originally Posted by GeoffR

It might be that other devices are overriding the size specified by the publisher. The problem with that is there is no way for an algorithm to know for sure what size the publisher intended, it requires some human judgement. Should it be relative to the screen size or to the font size? Did the publisher intend to have images 100% of screen height but only tested on a 600x800 screen, or did they intend 80% but only tested on a 758x1024 screen? Any automatic resizing algorithm is going to make some mistakes.

I think this is the same issue for a lot of other aspects of ebook display: does the device override the publisher's settings, which make books by bad publishers look better and books by good publishers look worse, or do they respect the publisher's settings so that books by bad publishers will look bad and books by good publishers will look good?

I edited the book using Calibre and used the option to resize the image. I set the image to a much higher resolution, but the kobo keeps showing it the same way. I can se the size diffence in resolution if I export the images, but keeps showing up really small on the kobo.

[GeoffR]

Originally Posted by Griu

I edited the book using Calibre and used the option to resize the image. I set the image to a much higher resolution, but the kobo keeps showing it the same way. I can se the size diffence in resolution if I export the images, but keeps showing up really small on the kobo.

That probably means the publisher has specified a fixed pixel size for the image in the HTML or CSS stylesheet. You'll have to use the second method in that case, and edit the HTML/CSS styles associated with the image.

It is hard to give a detailed example of how to do that, because there are a multitude of different ways the publisher can set out the HTML and CSS, but if you post the section of the HTML that refers to the image, and the associated CSS styles from the stylesheet then I can suggest something.

Here is a simple example from the last book I read (published by Random House UK) where the publisher has used a fixed pixel size for an image:
HTML:

<div class="part_image">
  <img alt="image" height="129" src="../images/part1_1.jpg" width="220"/>
</div>

CSS:

div.part_image
{
	text-align: center;
	text-indent: 0;
	margin-top: 10%;
	margin-bottom: 0em;
}

In this case the image contains a title in a font that is about 80px high. Resizing the JPG file has no effect because the height and width have been set in the HTML.

If I simply remove the height and width then the image will be displayed at the pixel size of the JPG file, i.e. resizing the JPG file would cause the image to resize:

<img alt="image" src="../images/part1_1.jpg"/>

If I wanted the image to be sized relative to the height of the device's screen:

<img alt="image" style="height:20%;width:auto;" src="../images/part1_1.jpg"/>

If I wanted the image to resize relative to the currently selected font size, with the 80px title in the JPG corresponding to approx 3em font height:

<img alt="image" style="height:auto;width:8.25em;max-width:100%;" src="../images/part1_1.jpg"/>

[GeoffR]

One note I should add, although it probably doesn't affect you:

There is a bug in the KEPUB reader that can affect image size/position when using full-screen reading mode. It is one of the bugs fixed by the firmware patch named `Fix three KePub fullScreenReading bugs`.

[Griu]

Originally Posted by GeoffR

That probably means the publisher has specified a fixed pixel size for the image in the HTML or CSS stylesheet. You'll have to use the second method in that case, and edit the HTML/CSS styles associated with the image.

It is hard to give a detailed example of how to do that, because there are a multitude of different ways the publisher can set out the HTML and CSS, but if you post the section of the HTML that refers to the image, and the associated CSS styles from the stylesheet then I can suggest something.

Here is a simple example from the last book I read (published by Random House UK) where the publisher has used a fixed pixel size for an image:
HTML:

<div class="part_image">
  <img alt="image" height="129" src="../images/part1_1.jpg" width="220"/>
</div>

CSS:

div.part_image
{
	text-align: center;
	text-indent: 0;
	margin-top: 10%;
	margin-bottom: 0em;
}

In this case the image contains a title in a font that is about 80px high. Resizing the JPG file has no effect because the height and width have been set in the HTML.

If I simply remove the height and width then the image will be displayed at the pixel size of the JPG file, i.e. resizing the JPG file would cause the image to resize:

<img alt="image" src="../images/part1_1.jpg"/>

If I wanted the image to be sized relative to the height of the device's screen:

<img alt="image" style="height:20%;width:auto;" src="../images/part1_1.jpg"/>

If I wanted the image to resize relative to the currently selected font size, with the 80px title in the JPG corresponding to approx 3em font height:

<img alt="image" style="height:auto;width:8.25em;max-width:100%;" src="../images/part1_1.jpg"/>

Actually I checked and none of my books are setting a fixed size, all images in all my books show as this

<img alt="image" src="../images/part1_1.jpg"/>

[GeoffR]

Originally Posted by Griu

Actually I checked and none of my books are setting a fixed size, all images in all my books show as this

<img alt="image" src="../images/part1_1.jpg"/>

Well if the size information isn't being set in the HTML/CSS then the only place it can come from is the JPG file itself, so all I can suggest is to open up (edit: i.e. unzip) the .epub flle after it has been sent to the device and check the sizees of the JPG files. They must be getting resized somewhere along the way.

Beware that in the case of the cover, Calibe replaces the cover image in the book with the one that is set as the cover in Calibre when it sends the book to the device. But the other images should only get resized based on the output profile.

If you can't solve it then PM me with a link to one of the problem books, and I'll see if I can find out what is going on.

[Griu]

Originally Posted by GeoffR

Well if the size information isn't being set in the HTML/CSS then the only place it can come from is the JPG file itself, so all I can suggest is to open up (edit: i.e. unzip) the .epub flle after it has been sent to the device and check the sizees of the JPG files. They must be getting resized somewhere along the way.

Beware that in the case of the cover, Calibe replaces the cover image in the book with the one that is set as the cover in Calibre when it sends the book to the device. But the other images should only get resized based on the output profile.

If you can't solve it then PM me with a link to one of the problem books, and I'll see if I can find out what is going on.

Thanks. I'll try that and let you know.

I have another question, I don't know if I should open another thread for this. I've noticed a lot of ghosting on the Kobo Glo HD. when I open a book I can see the marks of the squares in the home page, also when I switch the pages O can see some letter are slightly grayed out where a letter was in the previous page. Is this normal on the latest software? I never had this problem when I used the paperwhite and to my understanding the have the same screen technology.

[GeoffR]

Originally Posted by Griu

Thanks. I'll try that and let you know.

I have another question, I don't know if I should open another thread for this. I've noticed a lot of ghosting on the Kobo Glo HD. when I open a book I can see the marks of the squares in the home page, also when I switch the pages O can see some letter are slightly grayed out where a letter was in the previous page. Is this normal on the latest software? I never had this problem when I used the paperwhite and to my understanding the have the same screen technology.

I have an old Glo (Pearl screen), some of this might be different for the newer Carta screen devices like the Glo HD, or for Reagl devices like the Aura. You might be better to start a seperate thread.

I experience a problem with the current firmware where after waking from sleep in a book the text on the first page can be very light. It has been like that for quite a while now. But after turning the page it returns to normal.

In the past I have seen reports of ghosts from the sleep screen when using a sleep cover to wake the device, but I don't have a sleep cover, and I don't know if that problem occurs in the current firmware.

I haven't seen any unusual ghosting when opening a book or when turning pages, but opinions on this vary wildly: some notice ghosts after one page turn and have to set their devices to refresh every page. Others go 128 pages without any problem (there is a firmware patch to allow the number of pages per refresh to be increased, or it can be done my manually editing the device's configuration file). I don't know if it is a difference in devices, a difference in settings, or just a difference in perception.

[Griu]

Originally Posted by GeoffR

I have an old Glo (Pearl screen), some of this might be different for the newer Carta screen devices like the Glo HD, or for Reagl devices like the Aura. You might be better to start a seperate thread.

I experience a problem with the current firmware where after waking from sleep in a book the text on the first page can be very light. It has been like that for quite a while now. But after turning the page it returns to normal.

In the past I have seen reports of ghosts from the sleep screen when using a sleep cover to wake the device, but I don't have a sleep cover, and I don't know if that problem occurs in the current firmware.

I haven't seen any unusual ghosting when opening a book or when turning pages, but opinions on this vary wildly: some notice ghosts after one page turn and have to set their devices to refresh every page. Others go 128 pages without any problem (there is a firmware patch to allow the number of pages per refresh to be increased, or it can be done my manually editing the device's configuration file). I don't know if it is a difference in devices, a difference in settings, or just a difference in perception.

I found the problem. It was my mistake. I was changing the size of the images in the original epub and then converting the epub so I won't lose the original. I changed the image size on the epub after converting them and it seems to be working now. Apparently Calibre doesn't convert images really well for the kobo glo hd.

Thanks for your help. I feel a little stupid for not trying this before.

[davidfor]

Originally Posted by Griu

I found the problem. It was my mistake. I was changing the size of the images in the original epub and then converting the epub so I won't lose the original. I changed the image size on the epub after converting them and it seems to be working now. Apparently Calibre doesn't convert images really well for the kobo glo hd.

Thanks for your help. I feel a little stupid for not trying this before.

I'm not exactly sure what you did here. But, calibre doesn't upscale images. It will downscale them based on the selected output profile. I generally recommend using the "Tablet" profile as it sets the sizes large enough that images will not be resized.

The other thing is that when you do a conversion to the same type, calibre saves the original as "ORIGINAL_EPUB". Any further conversions will use this, not the new file. This is something I always forget as I convert, fix a problem, do another conversion and lose the fixes.