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Old Nov 1, 2005, 2:42 PM   #1
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Hi guys, I was wondering about this, and when I saw so many responses on a previous question regarding raw vs tiff etc.. If I use an 8mp (sony f 828) and shoot in jpeg...who big can I go with it..... Now with a tiff file as there is so much more information, how big can we go with that (even though the pixel count is the same) I have taken some team photo's and wonder how big I can go, or what dpi I need to go to keep them looking good...

Thanks for your time,


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Old Nov 1, 2005, 7:46 PM   #2
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Keep the originals exactly as they came from the camera with no changes whatsoever. Those are your "digital negatives" - don't mess with them. Don't change the format (JPEG to TIFF) or change the EXIF data (DPI is just an arbitrary number in the EXIF header) of your original photos.

How large a print you can make from an eight Mp image depends on many things. One of the issues is the viewing distance: a large photo may look good when viewed from a distance, while a small one might not look good through a ten power loupe. Faces in a group photo invite close inspection.

Do some tests by getting prints made. To keep the price down, crop out a small part and make a 4x6" print. If the crop is 1/4 of the short side of theimage, you will be looking at a part of a 16x24".
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Old Nov 1, 2005, 8:29 PM   #3
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How large you can make an image (print) is dependent on both what the image is, the actual picture its self, and how far away you view it.

Some images really require high detail. A landscape without detail isn't that interesting. A face/portrait with too much detail doesn't look good (who wants to see every pore and blemish on someone's face?) Some images want to be slightly soft or out of focus, others require tack-sharp detail.

An image that needs to be sharp and isn't won't print very large before it looks bad. Some images might not be very sharp but they can be printed large because it doesn't matter. A oceanscape with rolling waves and blue sky can be printed large because there isn't a lot of detail.

Bill handled how far away you view it. I've seen some really great images at 10 feet that look bad at 2 feet. Of course, these were 13x19" prints... quite large.

Eric
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Old Nov 1, 2005, 10:36 PM   #4
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but just to clarify, it isn't about whether the image is in tiff, or jpeg, or raw, as the pixel count is the same. So providing the image is sharp, as there are about 100 people (a retail store's employees, in front of the store) a tiff will not go any bigger than a jpeg right?



Thanks billdrew, and eric s for replying, I was hoping you two would see my post.. thanks!!
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Old Nov 2, 2005, 1:05 PM   #5
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Ah, now I understand where you're going with that question.
In theory (and mostly in practice) it won't matter if its in TIFF or JPG.
But because the JPG uses distructive compression is it possible that you will loose detail (part of how JPG compression work is that it gets rid of detail to increase uniformity of data... which increase the amount of compression that can be done.)

So if you used JPG and either recompressed it many times (saved it, closed it, reopened it, saved it, closed it, reopened it...) or just used too high a JPG compression setting then you will probably end up with a better/larger picture from TIFF than from JPG.

But a well handled JPG, where you took care to preserve the detail... then you'll get the same size and quality out of the image. The limitations that that previous statement puts on what you can do might prevent you from doing what you want (if you edit the image over several days, shutting off your system every night then you'll recompress the image each time and loose detail. So you'll need to edit the entire image in one shot.)

Glad you appreciate the time/effort that BillDrew and I put into this forum. It's a fun place, with lots of nice, smart people. I appreciate that you appreciate our contribution.

Eric
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Old Nov 2, 2005, 2:40 PM   #6
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eric s wrote:
Quote:
In theory (and mostly in practice) it won't matter if its in TIFF or JPG.
But because the JPG uses distructive compression is it possible that you will loose detail (part of how JPG compression work is that it gets rid of detail to increase uniformity of data... which increase the amount of compression that can be done.)
In practise TIFF is useless if camera includes low enough JPEG compression for not losing details.

You could test it youself.
Take picture in TIFF. (this also gives the size of uncompressed image for reference)
Then open it in photo editor which includes some kind tool for optimising JPEGs, especially Paint Shop Pro has good JPEG optimizer which shows you effect of selected compression in image while in other window it shows original image.
Now just increase compression to highest setting which doesn't cause loss of details and compression artefacts and then save image using that setting to get filesize for this "threshhold". (PSP shows filesize already in JPEG optimizer's window)

But like it has been said if you edit picture and then save it for later editing always use lossless compression, use JPEG only for final result (or lossless format if storage space isn't problem). And use tighter compression only for separate images made for web and such.

And considering original image, regardless of its format you should always take backup of that to CD... well actually DVD blanks have equal price, way bigger capacity (useful for these large 4-7MB JPEGs KM A2 makes) and better error correction which is always good considering longevity of storage media.
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