I changed .zip to .epub and it still opens.

tatagi · 10-31-2022, 08:44 PM

I have a zip file containing hundreds of images (jpg, png ... etc)

and out of curiosity, I replaced zip extension to epub. (without extracting)

surprisingly, it opened in associated viewer, as if normal epub file is opened, with each file name forming table of contents.

again I tried changing to pdf this time, and it worked as well.

can anybody tell me what makes this possible?

I think I can simply use this for converting image to ebook format, instead of online converters.

but only problem is that even it opens normally, the scroll bar is not visible so I have to use arrow key to navigate through pages.

can I make it show scroll bar by default?

Aleron Ives · 10-31-2022, 09:15 PM

"EPUB" is not exactly a format. It's a collection of files that when combined create an e-book. Such files include HTML for the text, CSS for the formatting, and images. All of these files are compressed into a ZIP archive, which is why you can rename .zip to .epub and have the the contents open in an EPUB reader. Without the HTML and CSS, the EPUB reader won't know how to format the images, though.

jhowell · 11-01-2022, 10:00 AM

Your file containing only images is not a valid EPUB or PDF. Whatever software you have associated with those file types on your system is being generous in handling that file instead of just reporting an error.

10-31-2022, 08:44 PM	#1
tatagi Connoisseur Posts: 52 Karma: 10 Join Date: Oct 2022 Device: none	I changed .zip to .epub and it still opens. I have a zip file containing hundreds of images (jpg, png ... etc) and out of curiosity, I replaced zip extension to epub. (without extracting) surprisingly, it opened in associated viewer, as if normal epub file is opened, with each file name forming table of contents. again I tried changing to pdf this time, and it worked as well. can anybody tell me what makes this possible? I think I can simply use this for converting image to ebook format, instead of online converters. but only problem is that even it opens normally, the scroll bar is not visible so I have to use arrow key to navigate through pages. can I make it show scroll bar by default?

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10-31-2022, 09:15 PM	#2
Aleron Ives Wizard Posts: 1,039 Karma: 11500112 Join Date: Sep 2022 Device: Kobo Libra 2	"EPUB" is not exactly a format. It's a collection of files that when combined create an e-book. Such files include HTML for the text, CSS for the formatting, and images. All of these files are compressed into a ZIP archive, which is why you can rename .zip to .epub and have the the contents open in an EPUB reader. Without the HTML and CSS, the EPUB reader won't know how to format the images, though.

11-01-2022, 10:00 AM	#3
jhowell Grand Sorcerer Posts: 6,502 Karma: 84500001 Join Date: Nov 2011 Location: Tampa Bay, Florida Device: Kindles	Your file containing only images is not a valid EPUB or PDF. Whatever software you have associated with those file types on your system is being generous in handling that file instead of just reporting an error.