[LanceJ]

I was poking around the Hubble Site looking at their photos (duh) and keep coming across humongous image files like these. Are these files for scientists to use? Because it seems like one could enlarge something like this into a wall-size image & still have it look good (ever since seeing a similar mega-poster of the moon's surface while on a tour of the Johnson Space Center in the 80s I have been trying to buy something similar for my listening room).

And what exactly is a TIFF file anyway?

Thanks.

LJ

[SethH]

TIFF is a completely raw file. It has no compression at all. You likely could blow a 9.48MB TIFF file up very large, but also remember that it's not compressed at all. If you compressed that same image using the JPEG used in consumer quality digital cameras you're probably looking a a 4MB file (maybe less).

[Rob Gillespie]

Even though it's 9mb, it's not actually that big at all. 1777x1864 pixels at 72dpi. That's not even the resolution of a 3 megapixel digital camera.

The size, as Seth said above, is purely down to the file format. Saving it in .bmp gives about the same result. .JPG compression reduces file sizes down a lot at the expensive of absolute quality of image. Saving that particular image as .jpg with lowest compression results in a file size of 2.9mb.

I've done true 2400dpi scans of 35mm prints on my Epson scanner and they come it at around 3500x2500 pixels, or 20-25mb in uncompressed .bmp format. I've done photo restoration work from scanned prints and made the mistake of scanning an 8x10 at 2400dpi. The file was so big nothing would actually load it - over 1gb. Even at 300dpi scan the image was still over 300mb in size, though the image quality was beautiful.

[Scott L]

I heard rumors that the next format after HDTV will be raw TIFF files at 90fps

[David Lawson]

A TIFF (Tagged Image File Format) can be compressed via the LZW algorithm, but it's lossless (which means there is no loss of quality, unlike JPEG, which uses a lossy compression scheme). Printers and designers use them in desktop publishing applications on a daily basis.

I never use BMP at work, and use JPEG sparingly, since the quality degradation from anything but the least possible compression is glaringly obvious in most cases.

[Seth_L]

Tiff files also can be losslessly compressed with built in zip compression. They support color depths up to 64bit, and can support several layers (like Photoshop files).

[Chris]

TIFF files are heavily used in Astronomy. The reason is because some of the pictures you will get have very faint presentations of orange/white/etc. which are culled out if you JPG. So, because of the need for complete accuracy, only lossless formats are used.

[Bill Slack]

TIFF can use compression. For this use, it's likely a lossless compression or maybe just RAW. The most common you'll see on color images are LZW (same as GIF), Flate (same as PNG), JPEG and uncompressed.

TIFF itself is just a generic container with a fairly extensible set of properties that are allowed, and then contains a data block that can be all sorts of different compression formats...

It's basically impossible to find a 'universal' TIFF viewer because of this.

[Mike Lenthol]

Quote:

8x10...Even at 300dpi scan the image was still over 300mb in size, though the image quality was beautiful.

300px x 300px x 24bits x 8" x 10" = 21.6MB UNCOMPRESSED
You are doing something wrong

[Jeff Ulmer]

I routinely use files this big (and a lot bigger) in publishing. That is roughly a 4" x 7" image at 300 dpi.

[David Lawson]

As do I, Jeff.

Quote:

The file was so big nothing would actually load it - over 1gb.

I've worked with these as well. Someone needs a memory upgrade.