MobileRead Forums - View Single Post - k2pdfopt: optimizes PDFs for viewing on e-readers

ioo · 10-25-2020, 09:58 PM

Hi, sorry I am not having any success using this software to quote you.

"It should be keeping the text searching by default if you have MuPDF."

I downloaded the latest version from your website, it does show MuPDF however if I use the list of arguments I mentioned I will end up with a series of images inside a pdf. When I transfer that pdf to my Kindle I lose the ability to search for text using the Kindle search won't I?

"I presume you found a version with MuPDF so that -n works? In that case, yes, your analysis is probably correct. The -n option can put more strain on the particular PDF reader. It's typically faster to display a bitmapped PDF."

It is a huge difference, like if I try to open one of the pdf files on my Kindle the whole Kindle becomes unresponsive and frozen for 5 or 6 minutes. I can't turn the page or go to the home menu. The device is completely disabled. I don't see this with the original PDF, does this sound right or do you think there is some other problem? It would really be nice to have native text on my e-reader so I can search.

I will work on uploading sample images. I just noticed something when comparing the k2pdfop1 pdf to the k2pdfopt file converted to awz3 with Calibre.

When viewing the k2pdfopt pdf on the Kindle, the text is uneven. Like the letter "I" might have a thicker border on the bottom then the top. The word "Room" will have double thickness on the "o o" letters however the next word "door" will have thin o's. The work "Santa" will have a super thin "S" and double thick "t". A letter "e" will look like it has a fuzzy halo around it.

I can pinch to zoom and the letters render differently at a different magnification level. If I zoom in a lot it actually looks more consistent (although much more pixelated).

When I look at the same page of text converted to awz3, each letter is more consistent. If I really look carefully, I can see each "o" letter is rendered very slightly differently (one or two pixels out of place) but I can just barely see this. Looking casually the text looks quite consistent.

I cannot use the device zoom in this format, whatever I try it shows me a list of text sizes to change to but since I have a series of images it doesn't have any effect.

When I zoom in the pdf format I notice that the device shows me the text then it overlays some sort of processing on top of the letters. It looks slightly "thicker or darker" afterwards.

Could the differences be attributed to the different programs on the device rendering the same images differently?

If I look at the pdf file using the KDE pdf viewer- okular and the converted file using Calibre's built in ebook viewer, the text also looks slightly more consistent on the Calibre file.

Calibre is outputting a file that has slightly different dimensions than k2pdfopt, could this be the difference?

Could this be a resolution issue?

Is it possible to convert these images to a lossless image format or is this not supported by ebook readers?

10-25-2020, 09:58 PM	#1820
ioo Junior Member Posts: 3 Karma: 10 Join Date: Oct 2020 Device: Kindle	Hi, sorry I am not having any success using this software to quote you. "It should be keeping the text searching by default if you have MuPDF." I downloaded the latest version from your website, it does show MuPDF however if I use the list of arguments I mentioned I will end up with a series of images inside a pdf. When I transfer that pdf to my Kindle I lose the ability to search for text using the Kindle search won't I? "I presume you found a version with MuPDF so that -n works? In that case, yes, your analysis is probably correct. The -n option can put more strain on the particular PDF reader. It's typically faster to display a bitmapped PDF." It is a huge difference, like if I try to open one of the pdf files on my Kindle the whole Kindle becomes unresponsive and frozen for 5 or 6 minutes. I can't turn the page or go to the home menu. The device is completely disabled. I don't see this with the original PDF, does this sound right or do you think there is some other problem? It would really be nice to have native text on my e-reader so I can search. I will work on uploading sample images. I just noticed something when comparing the k2pdfop1 pdf to the k2pdfopt file converted to awz3 with Calibre. When viewing the k2pdfopt pdf on the Kindle, the text is uneven. Like the letter "I" might have a thicker border on the bottom then the top. The word "Room" will have double thickness on the "o o" letters however the next word "door" will have thin o's. The work "Santa" will have a super thin "S" and double thick "t". A letter "e" will look like it has a fuzzy halo around it. I can pinch to zoom and the letters render differently at a different magnification level. If I zoom in a lot it actually looks more consistent (although much more pixelated). When I look at the same page of text converted to awz3, each letter is more consistent. If I really look carefully, I can see each "o" letter is rendered very slightly differently (one or two pixels out of place) but I can just barely see this. Looking casually the text looks quite consistent. I cannot use the device zoom in this format, whatever I try it shows me a list of text sizes to change to but since I have a series of images it doesn't have any effect. When I zoom in the pdf format I notice that the device shows me the text then it overlays some sort of processing on top of the letters. It looks slightly "thicker or darker" afterwards. Could the differences be attributed to the different programs on the device rendering the same images differently? If I look at the pdf file using the KDE pdf viewer- okular and the converted file using Calibre's built in ebook viewer, the text also looks slightly more consistent on the Calibre file. Calibre is outputting a file that has slightly different dimensions than k2pdfopt, could this be the difference? Could this be a resolution issue? Is it possible to convert these images to a lossless image format or is this not supported by ebook readers?