It surprises me that after several thousand hours of using InDesign, I still don't know how to place an object and know what InDesign is doing. Amazing, really.
Playing around with CS6, I thought I'd jump into the Digital Publishing mode and see what goes. I really thought a pixel would have been a pixel, but nothing's ever easy in InDesign. I'd like my placed images to come in pixel-for-pixel. As it is, they come in with this formula:
Pixel Width (CS6) = Pixel Width (Image) * 72 / (Image DPI)
So a 989 crop from a slide scanned at 4000 dpi, comes in as a microscopic dot on the CS6 page, with a width of 989 * 72/4000 pixels. At least CS6 does the maths correctly and states the width as 17.802. But I would like the width to be 989 (as shown in the "W" box up top).
I'm not fussed about whether one image-pixel actually maps to one screen-pixel (that's probably beyond CS6), just a simple: if an image comes in as 989 pixels wide, then CS6 knows it is working with a 989-width image, and displays it as a decent-sized image and not a spec of dust.
What boxes do I have to tick to achieve that (other than typing in "400000/72 %" in the % box).
You are approching it from the wrong way, even though you say yourself that
> [a]t least CS6 does the maths correctly ..
What would you like, then? That ID does NOT take DPI in consideration?
There is no "box to tick" to work in pixels. InDesign is designed to work with physical dimensions (since it's meant for print output, NOT screen -- pixel-based). "The" pixel as a measurement unit does not exist.
To work with pixels and live all of the side effects of that (such as that your image "dimension" will be different on different monitors), you need to work in a pixel-based program, such as Photoshop.