Images to grayscale

[Starson17]

Originally Posted by jackie_w

@scissors, I don't claim to know anything about News recipes but I've used the following command in my Calibre plugin to convert an image to greyscale

img.quantize(number_colors=8, colorspace='GRAYColorspace')

This code also works, although the image size increased to 43KB from 38KB.

[jackie_w]

Originally Posted by Starson17

This code also works, although the image size increased to 43KB from 38KB.

Oops!

[Starson17]

Originally Posted by jackie_w

Oops!

Well, the code was interesting. Thanks for that. Also, I can't be sure how the final compression in an EPUB would turn out. I just looked at the raw html/jpg output from the recipe.

[scissors]

Originally Posted by Starson17

That code won't do it. This will:

It saved 3KB from a 38KB image

It did indeed work! thanks

I did a SUN download, with and without it.

5.9m down to 4.7m

Thanks all who answered in this thread.

[Starson17]

Originally Posted by scissors

It did indeed work! thanks

I'm glad to hear it. I put the code into the Recipe code sticky for future reference.

[Starson17]

Originally Posted by scissors

I did a SUN download, with and without it.
5.9m down to 4.7m

Your 20% final is better than my 8% raw reduction. That's almost worth it.

[madeinlisboa]

Originally Posted by alansplace

i'd try this workflow:

1. convert to epub using calibre
2. use calibre's right click option 'tweak epub' to explode the epub
3. use IrfanView (free software at cnet) to batch convert all the graphics files.
4. rebuild the epub using the tweak epub window (it should still be open).
5. convert the epub to mobi with calibre.

That's what I call a great tip! Thanks!
I didn't use IrfanView but FastStone Viewer. The size of one of my epub files went from 18mb down to 5mb (almost a 400% decrease)!

This is the best method by far, because you can totally control the final image parameters.

Thanks a lot

[Starson17]

Originally Posted by madeinlisboa

TThis is the best method by far, because you can totally control the final image parameters.

I suspect the same level of control is available using ImageMagick if you get the parameters right. From what I can tell ImageMagick is fairly powerful.