The discussion came up on another board–of a customer (a customer of someone else, not me) requesting the scanning of photos and documents at insane resolution (2400 DPI, and many docs are large-format/oversize). I contend that they just happened to try scanning one doc themselves on their home scanner at its maximum resolution–and their PC/image program choked, so they figured a better computer could do it. (not that 2400 DPI is really necessary but anyway)
So I have a older copy of Photoshop (ver 7) and its maximum pixel size is 30K x 30K… but I remember reading somewhere the maximum image sizes of the different formats. And most can’t even go that big anyway. I think PNG max is like 1800 x 2400 pixels. Or something.
But I can’t find the image info online anywhere; does anyone know where has this info? Everything I find is discussing size limitations of different software, when I want to know the absolute size limitation of the different image file formats.
the way i understood it was that the different image formats were just the method for encoding (put simply some complicated maths) the image and as such there is no limit beyond the computer and softwares limits. so if you had a computer with no limitations and software with no limitations then they could be as large as you want. Of course theres probably a highest recorded size somewhere.
In the end what you can display comes down to bitmaps. The Windows bitmap format uses four bytes for both the width and height. So, theoretically you could have a 4 billion by 4 billion image loaded under Windows so far as the format is concerned.
In reality it will depend on the software you are using.
I could individually look up each format but my guess would be that the smallest max size would still be three bytes to an axis, so 2[sup]24[/sup] X 2[sup]24[/sup] or 16 million by 16 million.
There are limits in the file format based on how many bytes were allocated to hold a given value. A stream of compressed data doesn’t mean anything if you don’t know at least either the height or width of the uncompressed image.
GraphicConverter will not let me create a new document bigger than 64000 x 64000, and warns me when I try to do that that the mere 2 GB of RAM that I have is way insufficient. But then GraphicConverter, while a reliable everyday image-opener, is hardly the tool I’d expect to handle really large image files.
For big images, you need an app that has its own virtual-memory paging architecture, so that it can cope with huge images by paging chunks of it out to disk, which poor little GraphicConverter can’t do. Photoshop CS has a heartier appetite for pixels than version 7, unless DougC dropped a digit, and will allow me to enter up to 300,000 x 300,000 pixels for a new document, and the size of the resulting document is estimated at 335.3 Gigabytes. So now I’m wiped by hard drive limitation, rather than RAM limitaton (hey, I’m on a bloody PowerBook, I don’t expect to be toting around 335-gig files!)
The GIMP is more willing to create considerably larger images than Photoshop is. Ol’ GIMP says I can generate one that’s 16,777,216 pixels square. And tells me to be prepared to save an 805,306,368 MB file to disk when I’m done editing it. That’s a 786,432 GB file. Damn, I left my 2-petabyte drive back at the office. Can you imagine running a 1° counterclockwise rotation on that sucker?
Anyone got the specs on TIFF? That’s the format the graphics folks use most often, other than Photoshop PSD for layered files.
Tiff is not a single image format, it is a file wrapper for image formats. If you encode a Gif inside a Tiff, you get the Gif limitation, etc. There are many, many image formats used within Tiffs. The question basically cannot be answered in general.
Well nuts. My copy is an older version (Photoshop 7) and it is also a student edition. But if you try to make a new image with over 30K pixels either height or width, it stops and alerts that 30K is the maximum limit. Oh well.
Someone on another forum was hired to scan a bunch of old documents/pamphlets/books and photos (all from an estate). The documents were specified at 300 DPI, but all the photos they wanted at 2400 DPI–and any of the photos are oversize, won’t even fit on a refular flatbed scanner. Also–the materials cannot be disassembled or damaged during scanning; even pamphlets that are stapled together cannot be unbound for the scan.
Others questioned the wisdom of scanning photos at so high a DPI, but it was one of the customer’s main specifications.
Most archival/overhead scanners others found were only good for 600 DPI or so.
The guys at the Gigapixel Project originally found that no software could handle their requirements and they had to write everything from scratch. It took them many months after having the photograph assembled before they could even look at it because they still had to write an image viewer that could handle 1 billion pixels.
Note that is an upper limit. The individual encoding scheme may well have a much lower limit. E.g., I used to see MacPaint-style run-length encoded schemes that only allowed a single image size.
Well, compression is just whatever compression (if any) the particular encoding system uses. The compression can be LZW (which is really WZL), jpeg-style, whatever. A lot of Tiffs produced by digital cameras and scanners aren’t compressed at all. As to portability, you pay your money and take your chances. Maybe software X can decode a Tiff produced by sofware Y, maybe it can’t.