It’s widely acknowledged that the DjVu format excels in the online presentation of images/pictures, when compared with PDF, but this is not emphasized as much as it should be. In most discussions of eBooks, the emphasis is on text, and pictures are an afterthought.

This under-emphasis of commentators about the capability of DjVu in presenting books with pictures/images is perhaps related to the fact that the DjVu system itself has surprising design lapses that make it hard for the user to intuit the system’s graphic capabilities.

These powerful graphic features are especially related to use of thumbnails, which are much of what makes DjVu so useful for viewing books with pictures.

The thumbnail bar, shown to the left, is the key to navigating the pages of a book. The first hurdle in using this is that, oddly, the default display when a book is first displayed does not show the thumbnail bar. To turn it on, the user has to click the Show/hide thumbnail icon, which hides inconspicuously on the far right side of the toolbar. Turning on the thumbnail bar display can also be done by right clicking anywhere and choosing Layout – Thumbnails (In another odd, unaccountable oversight, the Show/hide thumbnail icon does not appear at all on the toolbar in the Macintosh -Safari version of DjVu, and the user has to use the right-click [or CTRL key] option to turn it on.)

The default display of the  thumbnail bar is quite small, so the next step in using it to get a better view of page contents is to enlarge the size of thumbnail images, by dragging the mouse, as shown at left.

The thumbnail bar works smoothly — Thumbnails are loaded rapidly as the user scrolls down to see more. Surprisingly the speed of loading seems to be little affected when the size of thumbnails is enlarged. It’s odd that the default size of images in the thumbnail bar is so small, when the larger size works so well — Another indication, I think, that the DjVu developers are not thinking much about use of the system for viewing books with pictures, since it’s so much easier to see details in pictures with larger thumbnails.

Finally, one more hurdle to using DjVu seems to exist in Internet Archive, which is the largest source of DjVu records — When the DjVu format is chosen in the “View the book” box, the link to open the DjVu file is broken. The way around this is to click All Files: HTTP, which is at the bottom of the “View the book” box. This goes to an index screen listing several formats, and clicking the one that ends in .djvu (usually the first in the list) successfully opens the file in DjVu format. I sent a question about this on Sept 8 to the DjVu.org forum, and have not gotten an answer on Sept 10 — Go here to see the question and to see if it has been answered.

Yogi Berra quote of the day: “You better cut the pizza in four pieces because I’m not hungry enough to eat six.”

Shown below are the “intro” pages for the book in the 2 systems. The clear advantage of the GBS intro page is that the sample thumbnails in the lower right make it immediately obvious that the book has COLOR pictures of good quality.

In Internet Archive the main job of intro screen (below) is to direct the user to options to view the book, in the box in the upper left, and there’s no indication that the book contains pictures.

Even after pulling up the DjVu option to view the book — which is a tricky matter, see how to do it here — there’s no intro screen at all in DjVu, just an imposing blank page waiting for the user to change display options or begin paging through the book sequentially.

It’s when the user chooses display options and begins viewing the book that the advantages of DjVu become evident. The most important option, especially if pictures are an important part of the book, as they are in the Mracek Atlas book shown here, is to turn on the thumbnail display bar (at left) by clicking the icon in the lower right corner of the DjVu display window. It then becomes easy to scroll through the thumbnails and get a good view of the nature of the pictures in the book, and how they relate to the text. In the Mracek Atlas, it happens that the first third of the book is all text, and the last two-thirds is mostly pictures, so the user can scroll to the pictures easily.

Use of thumbnails is a good way to provide access to pictures in a book. But as simple and obvious as it is, thumbnail access is lacking in most e-book systems, so both GBS and DjVu are to be applauded for providing it, in their different ways. Here’s a comparison of the two systems …

In GBS, the About this book page gives immediate thumbnail access to a maximum of 30 pictures. Additional pictures have no thumbnail access, and can only be found by scrolling through pages or text searching.

DjVu has the disadvantage of having no Intro page that gives an overview of pictures in the book. But when the user knows how to set the display options, it provides good thumbnail access to an unlimited number of pictures. In a book like he Mracek Atlas, with over 100 pictures, this is a definite advantage.

Postscript: It wasn’t easy to find a book that’s in both GBS and IA, so I was especially pleased to find the Mracek Atlas discussed here that has pictures in Hardin MD! The full citation for the book is: Atlas of diseases of the skin, by Franz Mracek, 1899 [GBS | IA]