FYI- IBA 1.1 image resampling to account for retina display

If you want your ibook to take full use of the "The New iPad" retina goodness

then your original image pixel size should be twice what it says in the inspector.

So if you pop a image in and size it and the inspector says 500w x406h

and you know the original image is only 550w x 450w it will not be using the full resolution of the retina display.

also if your original image is more then twice what the inspectors says IBA will down sample it.

even if by just a few pixels

your image original pixel size should be twice what it is displayed in the inspector(after you scale it to your liking).

anything higher IBA will down sample it to twice the size.

not a problem, but it doesn't make a difference to have it be larger.

so if your inspector shows image is 400pt wide(when you have it at the size you want)

and the original resolution is 1000pix wide, IBA will resample to 800pix wide

if the original image is 5000pix wide IBA will resample to 800pix wide.

If the original image is less then 800pix wide IBA does not resample it. (but you are also not taking advantage of the new ipads full resolution. May not make a big difference, will have to wait and see)

IBA will convert pngs(non transparent) and jpegs to jpgs with a medium/low setting compression.

so a JPEG with a "high" quality compression (small amount of compression) will be re-compressed to a medium/low quality.(more compression)

I don't remember if IBA 1.0 re-compressed jpgs. to a med/low quality.
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if your book had lots of PNGs, you will have a smaller file size with 1.1 due to conversion to jpgs

if it was mostly jpgs, you will have a lager file size with 1.1 due to resampling at 264dpi instead of 123dpi

it would be nice if you could choose the amount of compression of the JPGs. But I'm guessing on a retina display you would not be able to till the difference, or there would be little difference between a "high" quality compression and a "medium" compression.

As far as settings in photoshop, I would not down sample or recompress your images before placing in IBA.

keep your original images at their original settings.

I would let IBA do the resampling. just note that if it is less the 256 dpi it may not look as good, we will see.

and don't up sample to get the higher res.

If you have a monster file that is really huge, yeah, you could down sample in photoshop just to make it manageable.

Cropping yes, do in photoshop, IBA does not crop

and this can affect image quality, will explain later.

When we have a new ipad to test on we can see if having all your images at 256dpi is worth it.

My test were all based on looking at the files after exporting as a ibook.

(unzip .ibook file and look at assets)

FYI - IBA actually down samples to 144 dpi at a page size of 14.22 inches.

14.22" page size is the magic number to get Pages to import into IBA at the same size.

< it only needs to be twice its size to render correctly in the new hi-res iPads>

Yes, thats it.

Bottom line.

If you want to author for the retina display use the highest quality hi res images you have and let IBA do the rest.

if you are getting a stock photo etc for a full page background it should be around 2048 pix wide

But If you need to manage file size, or want control over the down sampling (sharping etc.) or don't care about the retina display (hey, there are more ipad1/2s out there)

then you need to down sample your images outside of IBA and make sure they are below the 264dpi that triggers a down sample with IBA

Fabe,

I would not downsample (size or compression) in photoshop. Keep your images at their best quality when placing in IBA.

You want to avoide multiple resampling.

Let IBA do the down sampling/recompressing. (it is going to do it anyway)

Use photoshop for croping and color adjustment etc.

Also this is good practice for the future, when the "new new new ipad" comes out with a dpi of 6000x4000...

you will not have to mess with all your images, just re-export with the the current IBA.

Always keep your master media files at their highest quality.

If you have super mega files that are bogging down your system,

then make new copies that are downsized but still quite a bit larger then what IBA will down samples to

You want to avoid down sampling at close to the same size.

MrBlobby,

My test were done with straight images placed on the page. I have not looked at what happens to images placed in widgets, or made to go fullscreen etc.

if you place an image that is 2048 x 1536pix(origina size)

and scale it to say 512pt x 384pt, IBA will down sample it to 1024pt x 768pt apon export.

I will take a look at what happens to images that are in widgets and go full screen etc. and let you know.