Originally Posted by nrapallo
I haven't tried this but it should work if you use as the largest size:
[*] Max. usable: 397 x 595 or
[*] Max. practical: 393 x 590. (better as avoids bleeding into the edge of the device and accomodates a 2px margin per DaleDe's suggestion)
The eBook Publisher then can "automatically" resize it to fit the devices' max. usable dimensions WHILE preserving the aspect ratio 320/480 or 0.667.
Great Idea, Jon!
p.s. likewise for other devices this would be:
[*] Amazon Kindle: Max. usable: 427 x 640 (and Cybook Gen 3)
[*] iRex iLiad: Max. usable: 623 x 935
[*] Sony PRS500: Max. usable: 502 x 753
[*] Sony PRS505: Max. usable: 512 x 768
So, in the end, the largest size for the 320x480 aspect ratio should be 623 x 935 (or rounding to 620 x 930) This would especially be useful for cover images!!!
please forgive me if i don't try to do the maths myself... but, with your measurements, are you taking into account the space required by running headers (i always use them) and side margins (same)
? i know some people do not use these, i *always* do and wish everybody would ! this is how i ended up at my original "usable" screen size of 310 x 430 px
for the eb1150 (i might be able to squeeze a few extra pixels in, but at that size i am *sure* nothing will get cut off. as i said, this size is only the result of my own personal experience so not completely definitive as the maximum possible size, but pretty close).
that said, the idea of finding a proportional size which will scale correctly on all displays is really great !!
it's rare to have full-page images but when you do, it would be really nice not to have to resize them individually each time you make a new format...
please note that my system above can be automated for batch treatment
(in photoshop, at least... that's how i'm doing the Austen images).
for example, in one of the books, the tallest image is 800px, but height and width varies with each image. so to easily equalize all images, i choose the format of height 800px for all images, and treat them automatically like this :
1. create a "dummy" image of the useable dimensions of the screen
2. on dummy image : image size, verify that the dimensions are linked, change height to 800px ; copy resulting adjusted WIDTH (this step is simply to avoid having to calculate it myself)
3. create script in photoshop :
- canvas size (ctrl + alt + c), change WIDTH to the adjusted width found in step 2 (for 800px height, width is 577px)
verify in the canvas size diaglogue, horizontal center and background extension color is white.
4. run this script on all the images of your book.
you can modify this script for any
set of images if :
- all are portrait format,
- the original proportions are longer / narrower than the display proportions, and (if they are shorter / wider, its not necessary, eBook Publisher will resize them automatically to fit the width of the screen).
- the original dimensions are all relatively close (i would say a variation of about 20 or 30 pixels height MAXIMUM for an 800px height, and obviously less is better).
for example i have the same script for a 600px height as well : new width is 433px.
the automation becomes more problematic if the original image sizes are wildly different, however in this case you can simply first add a step which will harmonize all the images by reducing them to one same height (/!\
ALWAYS reduce size, never enlarge !! or you will lose image quality).
Maybe this information could be added to the BEST PRACTICES wiki page ?