[Tex2002ans]

Originally Posted by jwes

I am converting OCR text of old magazines into epubs and have some questions.

1. How should I balance image quality and size? What size should I try to keep my epubs under to be easily usable? The images are not fine art and often not even good art. I have been downsampling and saving with reduced quality, but do not want to go too far.

There was a few topics way back in:

• 2013: "What’s your “image rehab” routine?"
• 2015: "Image cleanup tips"

Some people prefer manual image cleanup/steps.

Like others already said though, it sometimes helps to:

• Convert backgrounds to pure white
  
  • By adjusting the contrast/levels.
• Convert lines to pure B&W or grayscale
  
  • 256 or less shades of gray.

that will severely cut down on filesize.

See some of my discussion here on some potential tools/methods/examples:

• 2020: "How to handle images in books while doing OCR of books?"
• 2020: "Optimize PDFs from archive.org for E-Ink devices"

That covers a lot of the "yellowed pages" and similar issues.

Personally, I have zero image editing skills, so I mostly rely on the semi-automated tools to get me an "okay" image out of the original scans.

Originally Posted by jwes

2. Some of the pictures have text in blank spaces and I don't know if I can do that in html. I am attaching one of the more extreme examples and I would like to know what other people would do with it. It is two pages.

For oddly shaped images—like one with text below the horse's hooves—it's best to completely cut the text out of the images and replace with pure blank background.

Like DNSB + JSWolf said, from there, you could mess with code for "L-shaped images", but those are very tricky to make work, plus each image will require manual code/tweaking.

- - -

Side Note: In the future, there might be better support for this type of thing with CSS3 Shapes + automatic shapes based on the image's alpha/transparency:

• MDN: "Shapes from images"
• MDN: shape-image-threshold
• CSS Tricks: shape-image-threshold

but for now, that advanced code probably wouldn't work well in most ereaders.

- - -

Side Note #2: For more, similar discussion, also see:

• 2021: "Background Image w/ Text on Top"

Originally Posted by Turtle91

Personally, I would also stitch those two images back into a single image. That makes it much easier to flow the text around or otherwise manipulate.

Yep! Exactly! Merge the left/right halves of the horse together into a single image.

Then you could just plop the image into the ebook and treat it like a normal rectangle. :P

But to try to recreate some of these advanced two-page-spread layouts in an ebook... probably not the best idea!