How large of an image can Image-Pro Plus open?
Like so many other questions, the answer to this is essentially "Your mileage may vary". Image-Pro Plus is 32-bit software, so even on a 64-bit machine and operating system there are Windows-imposed limits on the amount of memory that is available to Image-Pro. This in turn limits the maximum size of any single image frame that can be opened. Image-Pro Plus uses memory management so that if you can load any single frame from a multi-frame sequence, you should be able to load the entire sequence - but it likely will not all be in memory at any given time. So the major limitation is imposed on the X and Y dimensions of the image.
There are things that you can do to maximize the size image that you can load. Contact Customer Service and ask for a white paper on "Working with Large Images".
Comments
I've found that very wide images render incorrectly and so can't be used at all in Image-Pro Plus, though that maximum width varies depending on the computer I'm using - on a PC without a separate graphics card and 4 GB of RAM, I hit the limit at around 17,000 pixels wide but on another machine that has more RAM (so that Image-Pro Plus can take its full share) and with a graphics card, the limit is a bit past 21000 pixels wide.
Another issue is whether you can do anything with an image once it's open. I'm currently working with images that are 120 to 200 megapixels (10-15000 pixels square) and while I can open the larger ones, segmentation and counting don't work and taking a snapshot or creating a mask (essentially, creating a new image) will freeze the program.
Also, it's important to remember that file size and image size are separate issues - you can have fairly small JPEG files that render to dimensionally large images. In Image-Pro Plus, what matters is dimensions, not file size.
When taking snapshots (to burn in measurements or capture object masking) of large images, you might sometimes get an error along the lines of "Failed to create DIBsection". That means that the Windows GDI couldn't render a bitmap for Image-Pro Plus to use for the snapshot, probably because it ran out of graphics memory. This has happened to me with some large images, though I haven't seen it since installing the version 7.0.1.658 patch.
image size = number of pixels x bit depth
Number of pixels is simply Pixels in X x Pixels in Y.
Bit depth should take into account colour, so an 8bit colour image is actually a 24bit image (3x8). Floating point images require 32bit per pixel per channel.
Also, since most people work in megabytes, not bits there's a conversion factor. 1 Byte equals 8 bits, 1 KB = 1024 Bytes, 1 MB = 1024 KB.
So, in practice a typical frame from a Sony ICX285 sensor (QImaging Click, Photometrics CoolSnap HQ2, and many other scientific cameras), working in 12bit colour will result in an image that requires (1040x1392x12x3) = 52,116,480 bits = approximately 6.2MB. If you are using a motorised stage system to acquire a tiled mosaic image you can simply multiply that figure by the total number of frames to calculate the image size. Note that as Will said this is file format independent so saving an image as a JPEG a which results in a significantly smaller file size does not reduce the memory requirements.
Also, since many image operations require the software to not only hold the image, but also the result of operating on this image in the same memory allocation you must estimate that the real image memory requirement is essentially twice that of the frame itself if you hope to be able to do anything with the image once it has been opened.
Also, bearing in mind that you're not just using the memory to hold the image but you're also using it to run everything else about your computer (OS, anti virus, background processes etc) in practice, out of the 1.6GB we mentioned earlier you really only have access to closer to 1.0-1.4GB of RAM. So the largest image you can open and do anything with will be roughly that divided by two (remember we need to be able to hold the result of the operation as well) or about 500-700MB, otherwise you'll start getting into virtual memory problems which more often than not means crashes and hanging.
Also, as Will said, the maximum width or height of the image is about 17000 pixels regardless of total frame size and now you can practically calculate roughly the largest image size you can not only hope to open but also be able to process.
If you're looking for one number out of all this, then the maximum image you can reasonably expect to open and process in Image-Pro Plus (or almost any other 32bit graphics package for that matter), will be about 500MB in TIFF as long as the image is no wider or taller than about 17000pixels.