(sigh), Kindle/KPF format Blues...

[slowsmile]

@JSWolf...

"The thing I would do is make the images follow the image sizes for the width and let the height fall where is may to keep the aspect ratio correct. Test it in the current Kindle Previewer to see if it can be converted to KFX."

As I've already mentioned -- for an epub, if you want to upload to KF7, KF8 and KFX, then all your images will have to be either full-width or full-page images. Any other smaller image sizing will just give image problems in one or other of those formats. This problem also has nothing whatsoever to do with image aspect ratio.

"I think KFX is a big mistake. I also think not allowing KF8 only eBook s is also a big mistake. There are things you cannot do in Mobi and if you have to do them and there's no way to them properly in Mobi, then don't have Mobi available."

I disagree. I think Kindle have done that for very delibrate reasons that no-one has worked out yet. I also think that their KFX mods aren't complete yet -- there's more to come. After all, they wouldn't implement such significant changes for KFX for no reason would they? And maybe all will become clearer once all their mods for KFX are complete. Of course, it doesn't help our understanding much when the documentation for these new changes is non-existent on the web.

"Amazon is keeping things backwards in order to satisfy an outdated obsolete format. So publishers are doing stupid things in order for the eBook to work as Mobi. For example, using images of text that Mobi doesn't handle but ePub and KF8 do. "

Yeah, and what about KF8 format that Amazon has dumped?? With KF8 and KF7 at least we could format any sized image in our epubs. Now, we are only left with KF7 or KFX format and only have the option of full-page images or full width images or just suffer the consequences. That's a crappy choice for sure.

[slowsmile]

@Hitch....

"You're saying that simply using HDV-sized images, coded as KF8 (using %) and using the hidden/KF7 method will NOT work?"

I'm not saying it will not work, but because of the larger sized HDV requirement for images then on a KF7 display your image will go to full screen width by default because of the rather large image sizes required for HDV. The HDV image sizing compliance is shown below:

1. For 50% screen width, your image must be at least 600 x 900 px in size.
2. For 75% screen width, your image must be at least 900 x 1350 px in size.
3. For 100% screen width, your image must be at least 1200 x 1800 px in size.

The above HDV pixel sizings MUST be adhered to for all images on KFX devices or you will get image degradation. There's really no wiggle room here.

Let's take an example. Say you want to insert a banner-like image to be displayed at 75% screen width and you insert such an image that is in compliance with HDV for KFX for an image that is 75% of screen width. That means that your image used must be 900 x 1350 pixels in size for HDV compliance. The width value is the all-important value here. And if you see that image after running my AddKindleMediaQueries then it will look OK on KFX but, because that image is stored as 900 x 1350 pixels in the epub, the image display on your KF7 device will just default to full screen width which is not what you want -- you want 75% screen width.

But if you set all your images to real size in pixels to comply with KF7 image requirements, then after using my plugin you will get images that work on KF7 devices which are too small and which do not adhere to KFX's HDV image sizing compliance, so all such images will be degraded and look blurry and low quality on KFX devices as a result. I've also confirmed this through my own comparison testing. If you want to test this for yourself then you should use screen shot images with text; just stick those images into an epub(where all images are sized for KF7 devices) and run my media query plugin, which shows this problem on test particularly well either on a KFX device or in KP3. The text within those images will be blurry and unacceptable.

So for those images that have a width that is smaller than screen width -- how should you store those images in the epub? If you store them as real sized images(for KF7) or if you store them at a much greater pixel size for HDV compliance(for KFX) then, as I've shown, you are going to have problems either way. This also means that my media queries plugin may not work properly anymore for this new KFX format which p*sses me off more than just a little bit. I might even have to retire the plugin and remove it altogether from MR.

"If you use the large image sizes dictated for KFX, but follow the CSS for KF8 and KF7, like in your plugin--what happens, exactly?"

I think I've already answered your question above.

[JSWolf]

Originally Posted by slowsmile

@JSWolf...

I disagree. I think Kindle have done that for very delibrate reasons that no-one has worked out yet. I also think that their KFX mods aren't complete yet -- there's more to come. After all, they wouldn't implement such significant changes for KFX for no reason would they? And maybe all will become clearer once all their mods for KFX are complete.

Yeah, and what about KF8 format that Amazon has dumped?? With KF8 and KF7 at least we could format any sized image in our epubs. Now, we are only left with KF7 or KFX format and only have the option of full-page images or full width images or just suffer the consequences. That's a crappy choice for sure.

Amazon created KFX because Mobi/KF8 have already been cracked. The DRM has been cracked and the format has been as well. KFX was cracked so Amazon changed it so it's no longer cracked.

Amazon created KFX to keep lock-in alive. Amazon cannot dump KF8 or there will be a lot of Kindle owners who will not be able to read eBooks from Amazon. It's Mobi that needs to go. That is the format that's causing most of the issues.

Have you tried going full spec for the width and let the height fall as it may to keep the correct aspect ratio?

[Hitch]

Originally Posted by slowsmile

@Hitch....

I'm not saying it will not work, but because of the larger sized HDV requirement for images then on a KF7 display your image will go to full screen width by default because of the rather large image sizes required for HDV. The HDV image sizing compliance is shown below:

1. For 50% screen width, your image must be at least 600 x 900 px in size.
2. For 75% screen width, your image must be at least 900 x 1350 px in size.
3. For 100% screen width, your image must be at least 1200 x 1800 px in size.

The above HDV pixel sizings MUST be adhered to for all images on KFX devices or you will get image degradation. There's really no wiggle room here.

Let's take an example. Say you want to insert a banner-like image to be displayed at 75% screen width and you insert such an image that is in compliance with HDV for KFX for an image that is 75% of screen width. That means that your image used must be 900 x 1350 pixels in size for HDV compliance. The width value is the all-important value here. And if you see that image after running my AddKindleMediaQueries then it will look OK on KFX but, because that image is stored as 900 x 1350 pixels in the epub, the image display on your KF7 device will just default to full-screen width which is not what you want -- you want 75% screen width.

Caveat: I haven't tested any of this, certainly not recently. The demise of CS has left those of us still standing insanely busy, so testing is not really in our schedule these days, sadly (I always thought it was the fun part of the gig!). Having disclosed that:

So...you put an image in your file, that's 900x1350, right? That's the 100% size of the image, correct? For the KF8 coding, you tell it to display at 75% of the width of the screen, not to be confused with 75% of the width of the image. Right? So, on a large-enough KF8 device, say a Fire 10", it would display 75% of the relevant screen width. Whatever the pixels may be.

We run your plugin, or do our own math...and that would get us what coding, precisely, from the plugin, William, for KF7? Would the KF7 portion instruct the device to display that at 1350px wide? Or 75% of 1350px wide?

What if we don't use the plugin, but use the same coding, and write our own width display coding, and tell the CSS for "mobi" or 'mobionly" that we want it to be, say...what, 400px wide? (I also don't recall all the old KF7 screensizes off the top of my head, but the first-gen was 600x800, so I'm going with ~75% of the old 600px width). (I agree that the plugin may need alteration, or perhaps, a 2nd gen version, that does additional calculation--not what's the % size of the image, but what's the relevant size of the image on a KF7 device? I don't believe, sadly, that we have individual mqs for unique devices, eg. the DX versus the K1, etc., but...)

So, as always, we have KF8 coding (and presumably KFX) for the full size and KF7 set in pixels, using hidden to hide one from the other.

Do you think that the pixel dimensions are going to interfere with the KF8 coding, or...?

I guess maybe it's been too long since I had my own hands in the code, and did some testing, so I'm having difficulty envisioning the issue here. Yes, the HDX sizes are big, but at my firm, we use images that are those sizes and more, sometimes.

(SIGH). I guess this means I have to do some testing. Dammit. I barely have enough time to shower and get myself dressed these days.


Hitch

[slowsmile]

@SWolf...

"Amazon created KFX because Mobi/KF8 have already been cracked. The DRM has been cracked and the format has been as well. KFX was cracked so Amazon changed it so it's no longer cracked."

KFX or its subset, KPF, were created for many reasons besides just secure DRM. They created the new format to greatly simplify the creation of quality reflowable ebooks and paperback books. Fixed format ebook creation with Kindle Create still has many downsides. If you want to read about the Pros and Cons of using Kindle Create you can download my free ebook on using KC from the Kindle Format section using this link.

"Amazon created KFX to keep lock-in alive. Amazon cannot dump KF8 or there will be a lot of Kindle owners who will not be able to read eBooks from Amazon. It's Mobi that needs to go. That is the format that's causing most of the issues."

I couldn't care less about lock-in. I already know how to convert a KPF file to epub format using JP Howell's KFX Input Calibre plugin which would also allow me to upload my ebook to any other ebook retailers or aggregators that I desire. And as alternatives, I also have and use Jutoh, Scrivener and Sigil on my computer which can also create the epubs I want from a Word doc for multi-distribution. So lock-in is not really a problem for me.

"Have you tried going full spec for the width and let the height fall as it may to keep the correct aspect ratio?"

What if I want, for my own reasons, to insert images at 75% of screen width in my epub? You can't do that for for an epub that is formatted for KFX, KF8 and MOBI without problems. Best read my last post to Hitch for details.

[jhowell]

Originally Posted by slowsmile

I made the point in my longer post above that images must be formatted for KF7 in absolute pixels whereas images formatted in KFX must be formatted as percentage of screen width AND must also comply with KFX's HDV image sizings. Dual formatting your images using media queries will certainly cover formatting for KF8 and KF7 devices but it does not properly cover KFX devices because HDV compliance also requires that you must use much larger images for KFX than the images required for KF8 or KF7.

The Kindle Publishing Guidelines in section 9.4.2, Image Size and Quality Standards, call for a minimum of 300 ppi in a full screen (4"x6") image. They do not mention that applying to any particular format.

Do you have a reference for a different guideline that applies to High definition visuals (HDV) in Enhanced Typesetting?

Originally Posted by slowsmile

AAnd if I format and add all my banner-like images to my epub according to the KFX HDV spec as 75% screen width then all I'm ever going to get on KF7 devices is a full screen width image which is not what I want.

The images in MOBI7 books will tend to occupy a larger portion of the screen compared with how they display on newer devices. In my opinion if it looks the way you want in KF8 and KFX and is still readable in MOBI7 that is good enough.

This is outside of my area of expertise, but my understanding is that you can improve the handling of image sizes in MOBI7 by using media queries to display/hide different <img> elements tailored to each format. Use a style with percent height or width for newer devices and height and width attributes sized in pixels scaled down from the actual image dimensions for older devices. I assume that as an alternative you could use a separate reduced size image for MOBI7 without the need to specify its height/width since it defaults to the actual image dimensions. Hopefully someone will clarify this if I have it wrong.

(Edit to add: The post by Hitch prior to this one covers the above topic better than my attempt.)

How necessary is any of this? In my examination of books produced by major publishers I have not seen any attempts to provide special image fallbacks for MOBI7. Perhaps someone could point out an example of this being done.

[slowsmile]

@Hitch...

"So...you put an image in your file, that's 900x1350, right? That's the 100% size of the image, correct? "

No, that's not correct. For every percentage screen size, you MUST use the specified pixel size(normally for width) that is quoted and nothing else. So you can only use the 900 x 1350 px image size for images that are set to 75% screen size -- with no exceptions. If you wanted to use an image at full-page size then your image must be sized to 1200 x1800 pixels. Here is the HDV compliance defined again with some emphasis to make things clearer:

Used only for 50% screen width, your image must be at least 600 x 900 px in size.
Used only For 75% screen width, your image must be at least 900 x 1350 px in size.
Used only For 100% screen width, your image must be at least 1200 x 1800 px in size.

If you images do not follow the above guidelines for KFX images then your images will be low quality(blurry).

[jhowell]

Originally Posted by slowsmile

For every percentage screen size, you MUST use the specified pixel size(normally for width) that is quoted and nothing else. So you can only use the 900 x 1350 px image size for images that are set to 75% screen size -- with no exceptions.

Where are you getting this from?

My reading of the publishing guidelines section 9.4.2 is that this is a minimum (not an exact value) and only applies to “important images”. Not long after that the guidelines makes exceptions and later gives a minimum of 72 ppi needed to pass conversion.

[slowsmile]

@jhowell...

"Do you have a reference for a different guideline that applies to High definition visuals (HDV) in Enhanced Typesetting?"

I couldn't find the original link to the HDV definitions I used, but I did find the Amazon Kindle Publishing Guidelines, which has been updated for Enhanced Typsetting at this link. Refer to Image Guidelines - 9.4.2 Image Size and Quality Standards. There is a table that defines recommended percentage size to image size which is the one you want.

When I did an output comparison test between images(containing text) produced in a normal KPF file(images complied with HDV standard) versus an epub where the images were stored at their actual screen size in pixels(smaller images), the images and text in the KPF file were much sharper and less blurry than the smaller sized images used in the epub. You will also get the latter effect if you just use my AddKindleMediaQueries plugin in Sigil which was originally designed to dual format images for KF8 and mobi7 only(not KFX).

[slowsmile]

@jhowell...

"My reading of the publishing guidelines section 9.4.2 is that this is a minimum (not an exact value) and only applies to “important images”. Not long after that the guidelines makes exceptions and later gives a minimum of 72 ppi needed to pass conversion. "

What you say is fair enough. But I would urge you to test as advised in my last post because as far as I'm concerned, the images produced from an epub that uses images sized for mobi7(that are smaller than the HDV standard) always gave me blurry images when I tested the epub on KP3. But the images in the KPF file(as HDV compliant images) were much sharper. And if you are going to test this, it's probably best to use image with text like a screen shot or window snip. You should hopefully see that there is a quite difference in the text sharpness bewteen the KPF file and epub.

[Hitch]

Originally Posted by slowsmile

@jhowell...



I couldn't find the original link to the HDV definitions I used, but I did find the Amazon Kindle Publishing Guidelines, which has been updated for Enhanced Typsetting at this link. Refer to Image Guidelines - 9.4.2 Image Size and Quality Standards. There is a table that defines recommended percentage size to image size which is the one you want.

When I did an output comparison test between images(containing text) produced in a normal KPF file(images complied with HDV standard) versus an epub where the images were stored at their actual screen size in pixels(smaller images), the images and text in the KPF file were much sharper and less blurry than the smaller sized images used in the epub. You will also get the latter effect if you just use my AddKindleMediaQueries plugin in Sigil which was originally designed to dual format images for KF8 and mobi7 only(not KFX).

But, William:

These are the same exact image sizes that they've been specifiying since...2017, if memory serves. They updated 9.4.2 in 2017.2, clarifying the "minimum quality standards for images in reflowable" books. At that time, they added the grid, and they used the divisions, full-page, 3/4, 1/2, 1/4 and "small." Right?

So...in two years, going on 3, these have been the same image-size standards, and so far, nobody's hair is on fire. That means that companies like mine have been blithely carrying on, toodling along, doing the SOSO coding--percentages for KF8, hard pixels for KF7, all this time and..

Spoiler:

I haven't received a KQN yet for image quality or sizing or anything else.

(I know I shouldn't say this, 'cuz, soon as I do...)

We've been using these images sizes, utterly coincidentally, for at least...4, going on 5 years. We have a handout for our customers, that we've been giving out forever, that tells them to make sure that they give us images that meet those same sizes--again, it's coincidental, in that it's not based on the Guidelines, but of course, we can all do the same math, in terms of, a 4" wide device x 300ppi = 1200 pixels, etc.

I guess why I'm struggling here is, didn't you just say that if we use your plugin, we get the sharper and less blurry effect? Our coding at BNB is the same as what you do, effectively--separate MQs for KF8/7, hidden, yadda, with the pixel counts in one, the % in the other.

Did I misread what you wrote? Did you mistype? Does using your plugin address this and give us SHARPER, or not?

I swear, I'm not arguing. I'm trying to get some clarity here (YSWIDT?) on this topic. If using YOUR plugin, or similar coding, works, then...???

Is there some penalty, like, your book doesn't pass KFX HDV intake, or, that I'm not understanding? Does this affect KC, maybe, and not ePUBs, or...?

Is there anyone here (yoo-hoo, Tex, you little madman maniac) that has time to make a test ePUB or two for this?


Hitch

[jhowell]

Originally Posted by slowsmile

When I did an output comparison test between images(containing text) produced in a normal KPF file(images complied with HDV standard) versus an epub where the images were stored at their actual screen size in pixels(smaller images), the images and text in the KPF file were much sharper and less blurry than the smaller sized images used in the epub. You will also get the latter effect if you just use my AddKindleMediaQueries plugin in Sigil which was originally designed to dual format images for KF8 and mobi7 only(not KFX).

I am missing something about your explanation. It seems obvious that using lower resolution images will yield poorer results.

What are the dimensions of the two images you are using?

Why are you even using two different images instead of using “height=# width=#” to scale the larger image down to fit the older format?

[Hitch]

Originally Posted by jhowell

I am missing something about your explanation. It seems obvious that using lower resolution images will yield poorer results.

What are the dimensions of the two images you are using?

Why are you even using two different images instead of using “height=# width=#” to scale the larger image down to fit the older format?

^Me too. This is partly why I'm confused.

Hitch

[slowsmile]

@jhowell & Hitch...Well, if you don't mind, I'm not going to explain it all again for a fourth time. And I think that there is a part that both of you are ignoring. Yes, KF8 has an image standard but it doesn't have ET capability -- so it does NOT have an HD image sizing standard.

Both of you are more or less saying that there is no difference in the image standard between KF8 and KFX. So here's my question to you:

Does the HDV compliance requirement, which is part of ET, apply to both KFX and KF8? For me this is crucially the part that you seem to be ignoring or missing. The ET standard also includes an HDV image sizing standard for HD images(for HD support) which you already know about. To me that also means that the image sizing requiremnets for KFX MUST significantly differ from image dimension requirements for KF8, which has no defined HD image sizing standard.

@jhowell...I've noticed, when I convert to epub using your Calibre plugin, that all the original images sizes in pixels are actually reduced in size(in pixels) to their equivalent percentage screen sizes in the KPF file. I've also read, in the Limitations section of your release notes for the KFX Input plugin, that you say that the images produced in the KFX or epub will be of low quality. What is the reason for the low quality images in the KFX or epub output? I would also certainly agree with you that the epub images from conversion are low quality on test. I'm not trying to kick up any dust here, but there appears to be a contradiction in your views. On the one hand you seem to disagree with me about KFX images and HDV sizings affecting image quality and on the other hand, in your Limitations section, you appear to be agreeing with me, because the only reason those images are low quality can only be because they do not strictly comply with the HDV image sizing standard for KFX because they are too small in pixel size, which is probably what is causing the low quality image output.

When I have some time I will put up two images on this thread from the same ebook. These images will be the same images in each display, but with different image sizings, to let you see the difference in image quality.

[jhowell]

Originally Posted by slowsmile

Does the HDV compliance requirement, which is part of ET, apply to both KFX and KF8?

Amazon has not been clear about the connection between High Definition Visuals (HDV) and Enhanced Typesetting.

The Amazon Kindle Publishing Guidelines in section 9.4.2 Image Size and Quality Standards states a minimum quality requirement of 300 PPI for "important images", but does not state that those guidelines are specific to Enhanced Typesetting or HDV. Even version 2012.4, which long predated Enhanced Typesetting, stated "To future-proof the content, save images in 300 dpi or 300 ppi resolution."

The KDP Enhanced Typesetting help page says: "High definition visuals (HDV) support: Images are an important part of the reading experience and help authors tell their stories and engage with readers. With high definition visual support, Amazon improves on unique eBook experiences such as image zooming, pinching, and panning, and takes advantage of newer display technologies and device capabilities." It does not actually state what constitutes HDV.

The only mention of HDV in Kindle Publishing Guidelines was added in update 2018.2 and just repeats the quote from the help page.

There is a message built into the Kindle Previewer that states: "High Definition Visual Warnings (HDV) - These warnings are for images which does not meet high definition image bar of 300 PPI. We highly recommend fixing these issues to improve the quality of the book for the readers". According to that, 300 PPI is needed for HDV, but it does not tie that requirement specifically to Enhanced Typesetting.

In my research into KFX format, which implements Enhanced Typesetting, I have come across a different technical meaning of HDV. It seems that images that exceed 1920 pixels on a side are allowed in reflowable books in KFX, but not KF8, and books with those images are tagged internally as having yj_hdv 1.0.