Scanning, Resolution, Color Deth

[JPSuisse]

Hi there,

One of the posts I recently read got me to thinking about my scanning techniques.

Consider the following:
1) I'm shooting with an MP, a good lens and very often with Tmax 400. (I'm not developing myself though.)
2) I'm using a Nikon 5000 film scanner, Vuescan and managing all the images in Lightroom.
3) My monitor is a well calibrated, Cinema display. The monitor supposedly displays 16.7 million colors, according to Mr. Jobs that is...

The results I'm finding with this combination are:
1) I scan snap shots at 2000 dpi (negative size) as jpgs. These look good and are very small. These are of course 8bit grey.
2) What irks me is that scanning at a resolution of 4000 dpi (negative size) for the real artistic shots, using 16bit grey scale and using the option scanner raw really doesn't give me such a big advantage. Not only that, I can't tell much of a difference between 8bit grey and 16 bit grey. On my monitor I should see difference...
3) Interestingly, all the DNGs Vuescan makes at 16bit above 2000 dpi are 59MB large, when I make 2000 dpi scan the 16 bit DNGs are only 10MB large...

The conclusion I draw from all this is:
1) It looks to me like the potential of the camera, film, scanner combination is about 2500 dpi.
2.) For higher (usable) resolution I need to start using slower film.

What are other people finding on the issues of scanning and color depth?

Best, JP

 

[kuzano]

I think the 2500 max DPI is very real, but

I think the 2500 max DPI is very real, but

where I think the higher res scans will show up is not in the quality you see on comparing the base scan of 2000 vs. 4000 DPi. I think the higher res will not show a much greater quality looking at the images on the screen. I would like to think however, that when I re-sample the image to 300 DPI for printing, I will see the ability to print much larger with the 4000 scan than with the 2000 scan.

I am currently in the process of sorting this out myself, and will be interested to see from other posters if my presumptions are correct. In other words, if I print a 2000 dpi scan at 8X10, will the same image print at a relatively larger print size, if the optimal print output is 300 DPI for both scans??? Is my thinking correct? Will the payoff be on image output to print?

 

[Jamie123]

Scanning 16bit instead of 8bit will not give you any visible difference if you just compare the results straight from the scan. However, scanning in 16bit will give you a lot more information to work with in photoshop. Once you're done post-processing the photo and you can convert it to 8bit again.

 

[agianelo]

Look for the number of gray levels your monitor can display. I'm guessing it will be around 1024. The best I've heard of is 3061 gray levels, which is far less than the 64K levels that your scanner can produce.

 

[Pherdinand]

as said above - you will NOT see a difference between 8 and 16 bit until you start processing.
If you scan an image at 8 bit and dramatically change levels e.g., you WILL see the gaps. If you scan at 16 bit, do the same changes, you will see much smoother effect.

Once you finished, you can put them to 8 bit, and save space/memory.

All scanners are optimistic in their nominal resolution. This is true a bit to real film scanners as well, apparently.

I don't know Vuescan, and hwo it works with raws. It was too complicated to figure it out, so far. HOWEVER: what i know of it is, if you tell him to scan to raw, he scans only ONCE, and further ANY conversion is done on the file only. Most scan softwares do a pre-scan and a final scan, and any tine you change something you should rescan; this is not the case with vuescan. It is mentioned as its advantage i.e. you save time with no need for re-scanning; but there must be a compromise: either the RAWs are too big for smaller final formats (thus take too much space), or they are too small for bigger ones.

Finally: Do you see the grain of the film? You should. Even my flatbed allows me to see iso400 grain at 2400+ dpi scan resolution. Even fp4+ in diafine gives visible grain.
Going to slower film or finer grain processing will indeed "help" if thats what u need.

 

[aad]

I don't expect you'll see any difference between one or the other-the resolution will allow bigger prints without interpolation, but 2000 dpi might well be enough up to at least 8x10. You won't see any improvement in sharpness or edge definition.

As mentioned, the difference between 8 and 16 bit depth makes no difference in the way the picture looks unless you need/want a lot of post processing work. If you're trying to make photos and don't mess up on the exposure, you're just making a bigger file.

The difference between jpg and raw/tiff is, again, file size for all practical purposes, as you have now seen for yourself.

If you use a slower/finer grained film, you'll see an improvement in many areas-but it will show up on the 2000 dpi jpgs just as well as the enormous 16 bit mega raw files.

And if you use a commerial printer, they're going to convert it to an 8 bit jpg anyway.

 

[pevelg]

I use 2000 and 8bit with color slides, saving as TIFF. I then created a script in photoshop that removes noise, sharpens, adjust levels, and then a linear contrast increase, saving as jpeg. The result? The finished jpegs are around 2mb and look pretty close to the original slide. Is it perfect? Of course not. I keep my slides safe and if I want one for printing, I will rescan it with the higher res and depth and then editing the images one by one. The majority of what I scan does not warrant the huge file size or the need for elaborate post processing.

 

[JPSuisse]

Hi there, thanks for your comments all!

The key point that confused me was indeed the number of different greys my monitor can display. (Thanks agianelo!) Indeed, as many pointed out, the 16bit on the artistic shots I use only to have nicer histograms and more info to work with.

I'm interested to hear about kuzano's test and I will soon do the same and report.

Best to all.