Output Profile Importance and Switching ?

[unboggling]

How important is the conversion with Default Input Profile and whatever Output Profile when reading the same book on different types of devices?

For almost 2 years I've been converting to EPUB master copy with Conversion -> Common Options -> Page Setup -> Input Profile = Default Input Profile, and Output Profile = Kindle. Then auto-converted those master EPUBs to MOBI to read on Kindle. Occasionally I'd read other formats (original formats) such as PDF on iPad, but those usually weren't converted so the Kindle Output Profile wasn't applied.

Now I've got a Nexus7 Android, in addition to iPad and e-ink Kindles. So I changed Output Profile to Tablet. But now I realize I may not want to do that, because I've got thousands of EPUBs based on previous conversion from Original Format to EPUB using Default Input Profile, to Output Profile = Kindle. I don't want to reconvert them all from the originals to be Output Profile = Tablet. And I don't want to end up with a bunch of sets of books, each set converted to master copies using a different output profile every time I get a new category of device.

The screen size of the Nexus7 is just a little bigger than the Kindle and Sony e-inks, so I don't know how much difference that makes. One thing that is probably different: for Output Profile = Tablet, no resizing of images is done (per the mouse tip in Preferences), and I assume that images do get resized with Output Profile = Kindle, or with Output Profile = Sony Reader. But due to the similar screen sizes I don't think that will matter much. Another difference may be the font rescaling, though again because the screen sizes are so similar it may not matter much.

Questions:

1. How important is the Output Profile?

2. What other kinds of things does the Output Profile change?

3. Would I be better off sticking with Output Profile = Kindle from now on, no matter what device I end up reading books on, so at least the conversions would be relatively consistent throughout the library?

4. Would I have been better off using the Sony Reader Output Profile for those EPUB masters instead of the Kindle Output Profile, a recommendation I just now read in the calibre user manual Conversion section?

5. Or would I have been better off using the Default Output Profile for those EPUB masters instead of the Kindle Output Profile? (oh well, water under the bridge….)

6. Is this one of the primary reasons experienced users advise not to trash the original formats?

7. What Output Profile would you use if planning to read most books on Nexus7 for the next few months, but don't want to be locked into any one particular device?

8. What would you do with the legacy books in the library if you were in my situation?

[kovidgoyal]

About the only thing of importance the output profile controls is image size when it comes to converting to EPUB. Eink device output profiles mean smaller images.

[unboggling]

Thank you, kovid.

I'll do some more testing conversions EPUB to EPUB of books containing images with output profiles = tablet, kindle, and default, to see exactly what happens to images with each output profile.

[unboggling]

Originally Posted by unboggling

I'll do some more testing conversions EPUB to EPUB of books containing images with output profiles = tablet, kindle, and default, to see exactly what happens to images with each output profile.

Update. I did some limited testing. And noticed some small differences with the size of images, but with all 3 output profiles (tablet, kindle, default) images and text were readable on both Kindle and Nexus7.

I added a tag to my custom column for format quality, to all books in the library converted using the output profile = Kindle, and some recently converted using output profile = tablet. I'll continue tagging different output profiles. So I can search for EPUB masters that were converted with which output profile. For now I'll see how "tablet" works over time for other cases including converting from other formats.

[itimpi]

As far as I know the only difference with using different profiles tends to be with images (as you have found) that are re-sized if necessary to fit the resolution for the selected profile.

[unboggling]

Originally Posted by itimpi

As far as I know the only difference with using different profiles tends to be with images (as you have found) that are re-sized if necessary to fit the resolution for the selected profile.

Thanks for confirming. So it seems that most people with multiple kinds of devices don't worry much about this.

I suppose a more accurate automatic solution would require an auto-conversion for every Send, even if Sending the same format, with auto-selection of output profile based on device detected, which would have a time lag for the conversion that most users wouldn't want. I doubt I'd want that… And I suppose it's more complicated, there's the issue of which input profile and which output profile were previously used to produce the input format that is used in this auto-conversion...

[unboggling]

After further testing, I reset Preferences -> Conversion -> Common Options -> Page Setup profiles back to Input Profile = Default Input Profile, and Output Profile = Kindle. And plan not to change them for specific conversions.

Reasoning: I want to preserve consistency of conversions within the library, and the books are readable on various devices regardless of page setup profiles, though image sizes may not be perfect for a specific device. In the future if I ever need specifically tailored output for a specific device, I could temporarily set Input Profile to whatever Output Profile was used in the prior conversion, and set Output Profile to the recommended profile for the intended device, then reconvert. But I doubt I'll bother.

[Sparticuz]

kovid, with the change in the new Kindle PW's resolution, does the Kindle profile need to be updated or forked?

[kovidgoyal]

Certainly, a new output profile can be created for the PW, but it needs some developer to get access to one, or for someone to tell me what the exact *usable* resolution of the PW screen is. i.e. not the nominal resolution but the actual maximum picture size that will not be resized by botht he MOBI 6 and the KF8 viewers on the PW.

[Sparticuz]

How would one go about finding that out?

[kovidgoyal]

You'd have to create an image with bands or a grid create a mobi file with that image at different sizes and find the maximum size for which there is no distortion due to resizing.

[theducks]

Originally Posted by Sparticuz

How would one go about finding that out?

If you are worried about XY distortion, (stretch)
Put a Sphere on the test covers

[Sparticuz]

Originally Posted by kovidgoyal

You'd have to create an image with bands or a grid create a mobi file with that image at different sizes and find the maximum size for which there is no distortion due to resizing.

I sent a 1024x758 image to my 'send to kindle' address and the thing it put on my kindle had an image size of 735x544. I'm not sure if that's the useable image size or not.

[kovidgoyal]

GRiker did some testing to find the optimum image size, the next version of calibre will have a PW output profile (658x940)

[GRiker]

Here's the process I used to determine the maximum image size:

• Create a 1024x768 file with alternating blocks of 1-pixel lines, making it easy to spot resizing anomalies
• From that file, create a 128x768 horizontal strip and a 1024x128 vertical strip
• Create an epub with these images in different chapters
• Compile the epub with Kindle Previewer (or Kindlegen)
• Transfer the generated .mobi to a connected Kindle /Documents folder
• Open the .mobi on the Kindle
• Take a screenshot of each rendered strip (on the PW, touch upper right and lower left corners at the same time)
• Open each screenshot in an image editor, measure the rendered area
• Create an image with these dimensions (940x658)
• Add an image of that size to the epub, recreate the .mobi with Kindle Previewer
• Confirm lack of resizing anomalies on the Kindle with a magnifying glass

G