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Old Oct 3, 2003, 1:28 AM   #31
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Eric, see that 1600% up at the top? I use the Photoshop magnifier as much as it allowed me to. I just wanted to show the pixels.



I think I already know the answer to this, but that's what I thought earlier, all the times when I was wrong.... anyway, let me see if I can use all the information you've just helped me learn.

Suppose I know I will be making a huge enlargement of a picture I take, maybe 8 feet by 10 feet. Now, I capture this "raw" image in my camera. So, I need to save it as a 'tiff' or 'jpg' or something useable.

Obviously, I will try to save it in the "biggest" image size possible. Maybe that's an image of 4 million pixels, which maybe is the biggest image my camera can save it as. However, now that I know all the things you guys have been telling me, would the following make sense? Instead of saving it that way in the camera, would I be better off trying to find a way to save it to an even bigger size, maybe converting the raw image in my computer instead of my camera?

(Does a computer raw image converter have the ability to save images out to a larger 'tif' file size than the camera does?)


The above is hypothetical - I don't think I'll be making any images that big, but who knows, I just made an 80-meg file three weeks ago for a sign that we needed to make. I "drew" the sign in Photoshop. If I had to make a gigantic photo right now, I'd save it in the best mode my camera could do, however large that was. But, after reading what you've been saying, maybe I'm better off just saving the 'raw' file, and trying to get my computer to save it out to a bigger file than the camera was capable of doing?

What would you do? (No, you can't tell me to get an 8 x 10" view camera....... :-) )




..................I wonder if Steve can re-title this item. It's sort of changed direction.....
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Old Oct 3, 2003, 5:31 AM   #32
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Quote:
(Does a computer raw image converter have the ability to save images out to a larger 'tif' file size than the camera does?)
Yes - After you have processed your RAW, you can resize the image to any size, although you're not creating anymore detail by sizing it up (but loosing data points if you size it down), all the while 'manufacturing' more pixels and more storage space! The resulting picture can be saved as JPEG with all sort of compression ratio (ie you select it), or TIFF, again you select it as 8-bit(24-bit color) or 16-bit(48-bit color) before you save. However like I said before you're eating up lot of room for something you are not able to differentiate. Can you tell the difference between (255,255,255) and (254,254,254) black level that I posted before, let alone between (65535,65535,65535) and (65534,65534,65534) which are also the same blacks but @ finer 16-bit?

Most people don't calibrate their monitor which is way out more than a few bits dropped here and there would matter... See there's more finite (16.7 million vs 281475 million) shade which is fine for program and digital computers out-specifying one another, but your eyes are analog and see things approximately (your color preference even change with mood!) and would never be able to tell thoses millions of bits apart...
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Old Oct 3, 2003, 1:21 PM   #33
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Sorry, missed the number there. 1600% is a lot of zoom!

You touched on several things, and are generally right. I would separate the file size from the camera vs. file size in general.

You do touch on this but I'm going to point it out. All cameras support different file output sizes. That means either less resolution, more jpg compression or both. Then there is RAW. Some cameras support compressed raw, and some don't. Either way it will be propritary. (The D100 supports both, but compressed RAW is so slow as to be useless. uncompressed raw is rather fast so everyone uses that instead.) The benefits of using RAW have already been covered.

Once you get the RAW file off the camera then you convert it. I would suggest TIFF (if you have the disk space) if the alsolute most quality matters. It has a lossless compression which is nice. The first few times a jpg is recompressed is still quite good (and probably visually equivalent) but some quality is lost.

Then you have to enlarge the picture. This is done in an editor (photoshop or something else.) When you enlarge the picture you can add data to it, which is figured out mathamatically. This is fake data (i.e. it isn't in the original) but depending on the picture, the enlargement method used and the subject matter it can still look quite good.

To make that really large picture you'd need to figure out what the best dots-per-inch you'd need for the printer you'll use. This is the same problem for every print. How much data to you need to make the result (print/web/whatever) look good. But I get the feeling this ground you probably already know something about.

Quote:
Originally Posted by mikemyers
If I had to make a gigantic photo right now, I'd save it in the best mode my camera could do, however large that was. But, after reading what you've been saying, maybe I'm better off just saving the 'raw' file, and trying to get my computer to save it out to a bigger file than the camera was capable of doing?
Get a 8x10" view camera! Just kidding. For general use, I use the best jpg settings my camera has. I haven't wanted to deal with RAW yet. The diff in quality doesn't matter to me right now, maybe it will later. Now that I have 1 1G card that means I can store a reasonable number of RAW pictures. My 512MB card just wasnít big enough. I should look into getting some kinda of portable hard disk, but I donít want to have to carry it around.

NHL

I generally agree that visually, there is little benefit for 32 and 48-bit color. But for the calculations done in PhotoShop, I want to use as much data per pixel as possible. I should lead to better results (with good algorithms.)

Eric
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Old Oct 3, 2003, 5:13 PM   #34
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I guess I'm learning more - I'm getting closer to what you guys are saying.

The only remaining missing piece of that puzzle, is saving the 'raw' image to the 'tiff' file. As both of you have said, when I save the image to a similarly sized 'tiff', I'm going to lose a little. I guess it's true that people might not be able to "see" the difference.

What I was asking, is if I could save the image (still in 'raw' format) out to a much larger 'tiff' file, rather than save it to one tiff file, and then use Photoshop or something to save that to a larger file.

(My Olympus can save to a 4-meg tiff file.... Suppose I could save the 'raw' file to my computer, and then convert it into a 10 meg ''tiff' file. Would that be better, than saving it to the 4-meg tiff, and then using another program to open the 4-meg tiff, and save it to a 10-meg tiff?



I suspect you're going to tell me that if the camera can only save the 'raw' file to a 4-meg tiff file, the Olympus software on my computer would also only save the image to a 4-meg tiff file, so it's not possible to do what I'm thinking.
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Old Oct 4, 2003, 11:24 AM   #35
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There is a fundamental flaw in what you are saying. Don't think about the size of the file as what matters. What matters are the bit-depth of the pixels and the dimensions of the picture. Yes, that turns out to mean a "larger file" (files with more color depth and larger dimensions are bigger.) But that doesn't really matter (until you run out of disk space and have to back up to CD or DVD!) What matters is the type of data, not that there is a lot of it.

For example, TIFF supports loss-less compression. It isn't as good as JPG compression, but itís good. This means that the same TIFF file could be stored as (these are made up numbers) a 10MB uncompressed TIFF or 6MB compressed TIFF. The 10MB file is not "better" than the 6MB file. It is exactly the same picture, with exactly the same data.

Here is another example (more far fetched, but possible.) It is possible that you could have a 1000x1000 24-bit TIFF file that took... 2.5MB after loss-less compression (20% compression.) And you could have a different 1000x1000 32-bit TIFF file that was 2.4MB (40% compression. Lots of nice clear, consistant blue sky.)

Is the 2.5MB file "better" than the 2.4MB file? Ignoring the content of the picture, the answer is no. Having 32-bit color should allow more manipulation to occur before artifacts would show up.

Size of the picture doesnít really matter; what matters is the number of pixels and the bits-per-pixel.

Now to get to your question. If you are converting from RAW to TIFF (if quality really matters, and you have lots of disk space I would convert to TIFF not JPG.) then you probably only have once choice. TIFF. Maybe the Nikon supports compressed TIFF, but I doubt it. So you can only convert it to 1 TIFF format (it supports multiple JPG formats, but Iíve already touched on those.)

After you do the conversion, then you load it in to your favorite editor and then you can enlarge/interpolate it to your hearts contentÖ making the file as large as you want. But you make it larger by increasing its dimensionsÖ that the file is actually larger on disk is only a side effect.

Eric
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Old Oct 5, 2003, 11:28 PM   #36
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I originally entered this item in the wrong place - it should have been in the "Digital SLR" area.

Since then, you guys have taught me a ton about image files. I'm pretty sure I understand it now - if nothing else, I've got a much better "textbook understanding". I'd like to start doing some of this, so I get some "practical understanding".



Today I went to a local camera store in Miami, Pitman Photo Supply. They've got a shelf full of Nikon D100 cameras, and they're selling them for around $1300ish, as I remember. I spent an hour or so looking over one of them.

I never got to turn it on (no battery), but I did get to look everything over. I'm impressed. I was rather tempted to take one of them home with me! I've got a D2h on order, and while the D2h is likely to do what I want it to much better than the D100, it's still a lot more money.... As I'm writing this, I'm not sure what I ought to do - wait for what I really want, or get the D100 now.


.....my brother keeps asking me if I "want" one of these cameras, or do I "need" one of them. He's saying that I've got a perfectly good F4, and it's going to take a long time saving "film costs" to pay the cost of "going digital". The best answer I can come up with, is that I don't "need" anything new. What I've got now (F4, Olympus e-10 and e-100) will allow me to do whatever I've got to do. However, if I'm using my Olympus stuff, all my Nikon lenses are sitting around collecting dust..... I've gone round and round on this, and the bottom line seems to be getting something that will do just about everything I want it to do. The D100 comes close, but the D2h covers what I'd like to be able to do perfectly. In a long talk with Dana Mead, over at Pitman, his opinion is that if I get the D100 now, I'm eventually going to spend the additional money to get what the D2h can do.



To Eric and NHL... since both of you have a thorough understanding of what can (and can't) be done, let me ask this. When you guys take photos, not something "special", but just routine photos, do you use "raw" mode routinely, for the reasons we've discussed? Or, if you aren't shooting something "special", do you just take the images as JPG?
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Old Oct 7, 2003, 1:00 PM   #37
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I rarely use raw because I don't have a portable hard disk. I can fill a 1G card in about 2-3 hours of outdoor shooting. Since the raw images are about 3 times the so (or so) I would have to shot less. Now, some might argue that this isn't a bad thing (I'd be more picky and I'd learn more about what I like and dislike.) But right now, I like taking that many shots and seeing which one came out well.

You see, the pictures are so much larger than I don't have the capacity that I want/need. So I expect I'll buy a portable hard disk device like a Image Tank. Then I can dump my pictures to it while shooting on the other card and have huge capacity.

But I do use raw when I'm doing something I will probably never do again. Taking pictures of an Osprey guarding her nest with her 2 young from a kayak on the ocean. Will I ever be foolish enough to bring the camera out there again? Will they use that nest next year? So I took about 30 RAW pictures and the rest in JPG.

Another member of this forum (Klaus) takes RAW all the time with his D100 and swares buy it. But he as a device to copy his pictures of the CF card in the field.

I can appreciate the problem of staying with film and do you really need the D2h. For me is was much easier, as my camera was not nearly as good as the F4. But with an F4, you have a really good camera. Does it do all you want? Is it as good as the D100 (AF, metering, shots-per-second,...)? If so, you'll probably find the D100 a compromise. It might work for you, or you might hate those missed opportunities that the F4 would have captured. If you can live with the F4 for awhile, then waiting might not be that painful and the D2h should exceed the F4 in many ways. Could you live with a downgrade in DSLR abilities to save money? For some the money is very important, for others they can afford it so that argument isn't as strong.

Eric
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