Calibre Companion prerelease 3.1.1c

[chaley]

Originally Posted by jackie_w

@Charles,

Oops, not quick enough! I've emailed you 3 sample covers. Sorry for my low taste in literature

Thanks. Using these covers I worked out why drag/dropped covers were so full of artifacts. The default compression quality used by Qt when converting from bitmaps to jpg is 75, which is quite low. To test, I changed calibre to use a much higher quality number, and the covers are much better. They still aren't perfect, as apparently something in the image chain is still messing with the pixels, but the artifacts are much harder to see.

Changes submitted to Kovid. He may have a better solution.

[PatNY]

Originally Posted by chaley

My guess is that your huge covers are actually just slowing calibre down and buying you almost nothing. It will never be shown full size, so it is always being downscaled. The only advantage of keeping an original cover is to avoid multiple jpg compressions passes, because each one loses a little bit of quality.

I don't want you to think I choose large cover sizes gratuitously, so let me explain my rationale. The reason I do it is not for any viewing benefits in the Calibre interface; it's solely for the ability to view book covers at full size on high resolution devices.

I noticed that as the screen resolution of my devices has increased, fewer and fewer of my existing covers at more standard sizes (such as 800 x 550 or 700 x 350) would be shown at full size in certain reader apps. Two such apps with this limitation are Cool Reader and Moon+ Reader. In Moon, you can see the cover expanded but you have to click on the cover to zoom in on it. It's a separate step. On the other hand, if the pixel dimensions of a book cover are as large or larger than your device's screen resolution, it will be shown at full size automatically upon opening the book in either of these two programs.

The screen resolution of my current Nook is 1440 x 900. But I anticipate in the future moving to a device with an even higher resolution, such as the Nexus 7.2's 1920 x 1200 size. So, that's the reason I have moved to larger covers. To better meet current needs and to future proof my books a little bit.

I understand viewing covers at full size is not even a priority for some. I've even read comments from some people here saying they don't even use covers for their ebooks. But I'm a little bit of a coverholic and deem covers essential to not only enjoying a book, but for also being able to easily browse and mange my library visually. At any rate, there is a rhyme and reason to why I choose large book covers.

Again, thanks for taking the time to address this issue. I appreciate it.

--Pat

[jackie_w]

Originally Posted by chaley

Thanks. Using these covers I worked out why drag/dropped covers were so full of artifacts. The default compression quality used by Qt when converting from bitmaps to jpg is 75, which is quite low. To test, I changed calibre to use a much higher quality number, and the covers are much better. They still aren't perfect, as apparently something in the image chain is still messing with the pixels, but the artifacts are much harder to see.

Changes submitted to Kovid. He may have a better solution.

Thanks for taking the time

[jackie_w]

Originally Posted by PatNY

So, that's the reason I have moved to larger covers. To better meet current needs to and to future proof my books a little bit

That's been my rationale, too. I wonder if we're both deluded

[PatNY]

Originally Posted by jackie_w

That's been my rationale, too. I wonder if we're both deluded

Nah, just different!


--Pat

[PatNY]

Charles, I just installed Calibre 1.4 and found the tweak for the compression level for covers sent to devices. I cannot get it to work.

First I tried level 90 and saw no difference in the Mudbound cover. I then put it at 99 and still couldn't see any difference. So I thought I'd test it at 50 just to see if the setting was having any effect, and I still couldn't see any difference. The cover always looks the same as it did before the tweak (when the level was 70). I cannot get it to look like the version you showed the other day.

I restarted Calibre after every setting change. What am I doing wrong? Is there another setting someplace else that also has to be changed? Is it my Nook HD somehow or ICS?

--Pat

[chaley]

Originally Posted by PatNY

Charles, I just installed Calibre 1.4 and found the tweak for the compression level for covers sent to devices. I cannot get it to work.

First I tried level 90 and saw no difference in the Mudbound cover. I then put it at 99 and still couldn't see any difference. So I thought I'd test it at 50 just to see if the setting was having any effect, and I still couldn't see any difference. The cover always looks the same as it did before the tweak (when the level was 70). I cannot get it to look like the version you showed the other day.

I restarted Calibre after every setting change. What am I doing wrong? Is there another setting someplace else that also has to be changed? Is it my Nook HD somehow or ICS?

Pat,

Covers are resent only if the metadata changes in some way (the last modified date changes). Changing the value of the device preference does not touch the last modified date, so probably nothing is being sent to CC.

You can test this with Mudbound by selecting the book, pressing E to open the metadata edit dialog, pressing OK without changing anything, then connecting CC. You should see it download metadata for at least one book, and the cover image should change.

After verifying that the cover did in fact change after you do the above, if you want to resend all your covers then you must change the last modified date on all books. There are several ways to do that.
1) When a device is not connected, press the down arrow next to the library toolbar button, choose Library Maintenance, Library metadata backup status, then press Queue all books for backup.
2) If you have a "column built from other columns" (a composite column), click on that cell for any book, press F2 to edit the template, then press OK.
3) Go to Preferences, Add you own columns. Choose any custom column, press the I button to open the column's properties, then press OK. Restart calibre.

Also, by "tweak" I assume you mean the setting in the smart device driver plugin. True?

[jackie_w]

@chaley,

I don't believe I'm seeing a quality improvement either. To test I set the SmartDevice value to 99 and then added a very red cover to one of my test books in the calibre library which didn't originally have any cover. After doing a CC connect, I can see the new cover but it still looks pretty rough on the Details page.

[PatNY]

Originally Posted by chaley

Pat,

Also, by "tweak" I assume you mean the setting in the smart device driver plugin. True?

It's the drop-down menu that only appears at the top of the main window when you connect a device to calibre ... when you click the icon of the device. I selected "Configure this device" and then near the bottom of the window where it says "Cover thumbnail compression quality" I put in 90.

Is that not the right place?

I tried doing what you said, actually making a change in the comments section (see attached screenshot; I added the word "TEST") ... and still there is no apparent change in the quality of the cover.

Previously I had deleted the book entirely from CC, and resent the book and that also made no difference.

Is it perhaps my antique OS I am using, Windows XP?

--Pat

[chaley]

Originally Posted by PatNY

Charles, I just installed Calibre 1.4 and found the tweak for the compression level for covers sent to devices. I cannot get it to work.

Originally Posted by jackie_w

I don't believe I'm seeing a quality improvement either. To test I set the SmartDevice value to 99 and then added a very red cover to one of my test books in the calibre library which didn't originally have any cover. After doing a CC connect, I can see the new cover but it still looks pretty rough on the Details page.

You are both right. Sometime between when I ran my tests and when I submitted the code to Kovid, one critical line of code went walking -- the line that actually set the desired quality to what is in the configuration. The quality is stuck at 70.

I have no idea how I did such a stupid thing, but I did. As a consequence you won't see the improvement until next week, assuming I don't do something equally stupid again. Given my recent record, I won't ignore that possibility.

[jackie_w]

Don't worry about it, we'll live! I'm always a bit relieved when I realise it's not me being stupid.

Just to make more nuisance, on a completely different topic, please can you explain the following:

In my calibre tweaks 'Control how dates are displayed' I have the following settings

gui_pubdate_display_format = 'yyyy'

gui_timestamp_display_format = 'dd-MMM-yy'

gui_last_modified_display_format = 'dd-MMM-yy'

On the CC Details page,
Pub date and Added to calibre are displayed as 'yyyy'
Updated and Read are displayed as 'yyyy-mm-dd hh:mm:ss'

The only one I'd prefer to display differently is Added to calibre where 'yyyy' is not really enough info to be useful. Am I missing a setting somewhere?

[PatNY]

Ahhh, no worry. It's good to know it wasn't my antique OS or all just in my head. I can stop testing for now too.

I'll look forward to the next Calibre update next week.

A question: What kind of a a performance hit would I incur by setting the quality level to 90 or 99? Is it just the length of time it takes for Calibre to send new covers to CC? If so, I don't mind that at all. I am not too concerned with speed when importing books as that won't happen too frequently. Or will it slow down metadata sync on every single connect? That is a different matter and something to be concerned about.

Also, if a high setting and larger thumbnail file sizes will slow down CC -- ie, jumping from screen to screen and sorting on tags -- well then I will be more conservative with the setting and won't go above 90.

--Pat

[chaley]

Originally Posted by PatNY

A question: What kind of a a performance hit would I incur by setting the quality level to 90 or 99? Is it just the length of time it takes for Calibre to send new covers to CC? If so, I don't mind that at all. I am not too concerned with speed when importing books as that won't happen too frequently. Or will it slow down metadata sync on every single connect? That is a different matter and something to be concerned about.

My tests indicate that the cover grows by around 40% when compression is changed from 90 to 99. That will impact the time to send metadata either direction. It shouldn't significantly change the processing time to display the images.

As regards sending time, the new metadata caching stuff I am working on will make that much less of an issue. The next CC prerelease cycle that should start next week will send metadata to calibre only if calibre hasn't seen that metadata before. This means that the "sending metadata to calibre" time will be reduced dramatically. See https://www.mobileread.com/forums/sho...32#post2630832 for some timing test results.

What isn't clear to me is whether 99 is visibly much different from 90. I didn't see much difference, but then I am not a good critic of this sort of thing. Once the code works, let me know.

[chaley]

Originally Posted by jackie_w

Just to make more nuisance, on a completely different topic, please can you explain the following:

In my calibre tweaks 'Control how dates are displayed' I have the following settings

gui_pubdate_display_format = 'yyyy'

gui_timestamp_display_format = 'dd-MMM-yy'

gui_last_modified_display_format = 'dd-MMM-yy'

On the CC Details page,
Pub date and Added to calibre are displayed as 'yyyy'
Updated and Read are displayed as 'yyyy-mm-dd hh:mm:ss'

The only one I'd prefer to display differently is Added to calibre where 'yyyy' is not really enough info to be useful. Am I missing a setting somewhere?

This is a bug that has been there since the birth of CC. I am surprised that you are the first to notice. CC is using the pubdate format instead of the timestamp format to display the "added to calibre" (the calibre "date" field). I fixed this. CC has the right format for both of them, it simply used the wrong one to display "date".

CC doesn't display calibre's last modified date. The date you are seeing is CC's last modified date, for which there is no format modifier.

[jackie_w]

Originally Posted by chaley

This is a bug that has been there since the birth of CC. I am surprised that you are the first to notice.

Do I get a prize? or a pedant's award?