JPG and TIFF - driving me mad!

[pico]

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As far as I know jpg is a lossy compression process - in other words data is stripped from the image and thrown away - it's never going to come back. A jpg file will never get bigger and that's the issue with this processor. They advertise 18mb scans but deliver 2mb files. 

 

Sorry. You are right. I was thinking of lossless TIFF compression.

[dunhoy]

One solution is to scan your own film at the resolution and output file size you want - but I appreciate this may not be possible due to other constraints.

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[tobey bilek]

I think it is perhaps a bit of an overreaction. OK, if you wanted TIFF files they should have sent you them. But a JPEG is only lossy if you keep opening, editing, and saving it time after time. The first time opened any loss will be utterly insignificant from the image quality you could have got from an uncompressed TIFF, hence the company saying to save the opened JPEG as a TIFF, and this would be normal procedure if wanting to edit any JPEG. I don't think the company are trying to rip you off or anything, after all they will send out files to customers who have varying degrees of memory available so 2mb JPEGs (72mb for a roll of 36) are a convenient usable method instead of for instance dumping on an iPad user 648mb of TIFF data in one go.

 

Steve

 

JPEG are compressed and 8 bit colors.   There be no way to recover 100% what was thrown away especially 8 bit colors.    If you were to try to apply a gradient to 8 bit,  banding results.  A JPEG for me is reserved as a one off final product.  All previous steps are saved losses.   If you want a new size print, you go back to tiff scan or photoshop or raw file and work to new size using aformentioned formats as starting points.

 

My first digital camera did not save raw files.  I learned really fast. 

[250swb]

 

I think it is perhaps a bit of an overreaction. OK, if you wanted TIFF files they should have sent you them. But a JPEG is only lossy if you keep opening, editing, and saving it time after time. The first time opened any loss will be utterly insignificant from the image quality you could have got from an uncompressed TIFF, hence the company saying to save the opened JPEG as a TIFF, and this would be normal procedure if wanting to edit any JPEG. I don't think the company are trying to rip you off or anything, after all they will send out files to customers who have varying degrees of memory available so 2mb JPEGs (72mb for a roll of 36) are a convenient usable method instead of for instance dumping on an iPad user 648mb of TIFF data in one go.

 

Steve

 

JPEG are compressed and 8 bit colors.   There be no way to recover 100% what was thrown away especially 8 bit colors.    If you were to try to apply a gradient to 8 bit,  banding results.  A JPEG for me is reserved as a one off final product.  All previous steps are saved losses.   If you want a new size print, you go back to tiff scan or photoshop or raw file and work to new size using aformentioned formats as starting points.

 

My first digital camera did not save raw files.  I learned really fast. 

 

 

This is a bit irritating because I just can't find the bit where I said anything was 100% recoverable? I've wasted my time reading the thread all over again. If you want it summed up simply the difference between opening a JPEG and a TIFF side by side will be visually negligible, start to edit them both and the difference soon starts to show in favour of the TIFF. That is what I said.

 

I also went on to say that any small loss of quality in the initial stages of opening and closing a JPEG is usually well offset by many other things that can have more of an effect on image quality than the inherent problems of the JPEG itself. But I've already detailed that so won't say it again.

 

Steve

Edited July 6, 2015 by 250swb

[giordano]

I've had this problem too, and from what passed as a pro lab. NO question, compressing an 18MB TIFF to a 2.5MB has a cost in terms of fine detail and transitions.

 

A similar problem is the way smartphone cameras capture (say) an 8 megapixel image which would be 24MB as an uncompressed TIFF, but insist on compressing all those lovely pixels into a c. 2.4MB JPEG. I wish I could control the JPEG compression to get a less highly compressed file as a starting point, say 6 or 8MB.

[too old to care]

I just looked at some of my own scans.  I use a Plustek 7600i scanner, and there is a lengthy discussion someplace on this scanner.  So, I do not want to go there, but instead relate to what I see in file sizes.  The numbers are for B&W only.  

 

When I scan at 7,200 dpi (which I never do anymore) my tiff file sizes are 60MB plus.  Converted to jpeg they drop down to about 25 to 30MB, or about 1/2 the tiff size.  They also look pretty good when printed, close to what I get printing wet if I stick to 11x14, or smaller.  

 

Most of the time I scan at 2,400 or 3,600dpi.  Those file sizes range in the 16 to 22MB size.  Converted to jpeg they pretty much cut in half too.  If I stick to 5x7's or smaller, they pretty much look like my wet prints.  However, 8x10 is pushing it.  

 

That said, I serious doubt that my scanner can really scan at 7,200dpi, probably closer to 5,000.  I say that because I cannot tell any difference once I get above the 4,800dpi setting.  But, there is a big difference in the quality from using the 4,800dpi and the 2,400dpi settings.  

 

If I save the jpeg files to the 4 or 5MB, as to email them or post them, there is a big difference between the original TIFF scans and those files.  From what I can see, your lab is scanning at the low end of what could be done.  Then reducing the resolution by further cutting the quality of the jpeg scan.  

 

One last thing, getting the scanner also lead me to opening my darkroom again.  Sitting behind a scanner is no where as much fun as standing in front of trays of chemicals.  But, that is not the purpose of this post.  Scanners are cheap, and you can do your own work to your satisfaction.  

Edited July 6, 2015 by too old to care

[pico]

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TIFF has no loss unless you want it.