Book Trading Cards

With World Book Day nearly upon us, I was pondering ways in which children could be engaged with reading books.

I know how children enjoy trading cards like Pokémon, so could we encourage them along more wholesome lines, that don’t involve rarity and competition, and facilitate a discussion about what books they’ve enjoyed?

I’ve mocked up the front side of some trading cards:

I have yet to produce a design for the back, but I think the contents would include:

• Title and series of the book,
• Author,
• Genre,
• A small synopsis or teaser, and
• Five open stars at the bottom, which the children could fill in with a marker pen.

The covers themselves are normally so attractive that the front doesn’t need any extra adornment, apart from an appropriately-coloured border.

Producing the cards

In case anyone fancies having a go at making some, here are some notes on what I did.

I gathered the book cover images from Amazon. To my surprise, Amazon make this very easy. When you pick a particular book, beneath the cover image, which is often a link to their “Look inside” page, the cover image is directly available with a “See this image” link, and the image is large enough that it can be used to make a quality print on an inkjet at trading card size.

A standard trading card is 64mm x 89mm (2½" × 3½"). Because the proportions of the book cover won’t necessarily be the same as those of a trading card, they need a border. My first experiments used a rather arbitrarily-chosen dark blue, but it was clear that it was a really poor match for most books.

So, I’ve used GraphicsMagick to find a reasonable match from the colours used for each cover. There are often three or four colours which would work for the border, so I’ve picked one by experimenting with the histogram produced by GM’s “segment” function:

gm convert book-cover.jpg -segment 1.0x1.5 -verbose tmp.png

This will cluster colours in the image and tell you what the colours are with an RGB triple in hexadecimal, and a measure of how many pixels were in each cluster. The segment parameters here work for a lot of books, but occasionally I’ve had to reduce them to tiny numbers when the images are more photographic, at which point you might find it easier to pull the cover into a paint program and use a pipette tool to pick a colour you like.

As far as I know, you can’t direct “gm convert” to simply not produce an image as output, and if you direct the output to stdout and pipe that into /dev/null, you’ll lose the histogram.

I used GraphicsMagick to composite nine trading cards on an image sized for A4 paper at 300 dpi (i.e. 2480 × 3508 pixels.) There is at least a 5 mm border all round and roughly 2 mm between each one, which is plenty for someone with scissors and a steady hand.

I’ve printed my cards on 170 g/m² matte photo paper and then laminated them with a glossy sleeve.

I’d love to hear your thoughts on this.