# Scanning...resolution



## Josh66 (Jul 25, 2009)

What resolution do you guys scan at?

I usually scan at 6000x9000 pixels (20x30" at 300dpi).

I tried scanning some at 9000x13500 (30x45" at 300dpi), but I Windows Photo Gallery (default display program on my machine) can't display a file that big...  Even Lightroom has trouble loading it.

Surprisingly, GIMP has no problems at all.  


20x30 is what I scan everything at right now, I'd like to up that to 30x45 (never know how big I might want to print one day), but short of GIMP I don't have any software that can handle it...


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## Dwig (Jul 25, 2009)

It depends on what you are scanning. Given that your scan resolution is a 2:3 ratio and that you didn't bother to specify the format of the film you're scaning it seems safe to assume you are scanning 35mm images. Other formats are rarely 2:3 and users of such are generally alert enough to specify film size.

To get a 6000x9000 image from a standard 35mm original (aka 24x36mm, 35mm Full Frame, 35mm Double Frame) you'd have to scan are around 6000ppi, slightly higher at around 6400ppi if you are scanning mounted slides. This is generally excessive, few if any films retain adequate detail to require such high resolutions. Certainly none require anthing significantly more. You'd be as well off, possibly better off, not scanning at higher resolutions and upsampling afterward instead.

Personally, I don't scan 35mm at higher that 4800ppi unless I encounter an interaction between the film's grain and the scanning resolution. Such things do happen when the film grain is uniform and very close to 1 or 2 pixels in size.


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## Josh66 (Jul 25, 2009)

Dwig said:


> Personally, I don't scan 35mm at higher that 4800ppi unless I encounter an interaction between the film's grain and the scanning resolution. Such things do happen when the film grain is uniform and very close to 1 or 2 pixels in size.


I have heard of that, but haven't personally encountered it yet.


...Yes, I am talking about 35mm film.  Didn't think to mention it in my first post.




Maybe this is a case where less is more...  I will try scanning at a lower resoluton next time.  20x30 is likely the largest I will ever have anything printed, and even that will be only a select few photos.


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## Dwig (Jul 25, 2009)

O|||||||O said:


> Dwig said:
> 
> 
> > Personally, I don't scan 35mm at higher that 4800ppi unless I encounter an interaction between the film's grain and the scanning resolution. Such things do happen when the film grain is uniform and very close to 1 or 2 pixels in size.
> ...



Personally, I've only encountered it in a batch of 127 negatives that my grandad shot during WWI. One batch that seemed to be from the same roll were noticably grainier than others. The grainier ones scanned very poorly at the 2400pppi that I was using, which was yielding about 3200x5400pixel images. I dropped the scan resolution to 1200 (~1600x2700) and the images were much better; the interference pattern, a Moire like effect, was absent. Given the limited resolution of the simple 2 or 3 element lens in grandad's Kodak Vest Pocket Autographic, the lower resolution scan resolved all the detail in the image.

I've scanned at resolutions higher than 4800ppi a few times. These never actually captured any additional detail in the image, they just did a better job of resolving the grain or, in the case of color images, the dye cloud left where there was originally a silver grain clump. If the image is grainy enough, 

I find it better to get crisp rendition of that grain than let it go to mush. Artistically, I look at grain in much the way I look at the out of focus part of an image. I don't dislike grain, or digital noise for that matter. What I dislike in bad grain (mushy and/or uneven), bad digital noise (blocky, odd shaped), or bad bokeh (nasty, unsmooth, oddly shaped blurs from point sources). All three can be ugly or attractive.


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## Josh66 (Jul 25, 2009)

Dwig said:


> I don't dislike grain, or digital noise for that matter. What I dislike in bad grain (mushy and/or uneven), bad digital noise (blocky, odd shaped), or bad bokeh (nasty, unsmooth, oddly shaped blurs from point sources). All three can be ugly or attractive.



I agree 100%.  Grain, even noise, can be quite pleasing - if it fits the photo.


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## KD5NRH (Jul 26, 2009)

O|||||||O said:


> Maybe this is a case where less is more...  I will try scanning at a lower resoluton next time.  20x30 is likely the largest I will ever have anything printed, and even that will be only a select few photos.



If you're going that big, it's probably worth the effort to do it in the darkroom and skip the computer altogether.


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## DSPhotography (Jul 26, 2009)

What kind of scanner do you have? I'm just thrown off by you saying you're getting a 6000 x 9000 image but only with 300dpi as that's about the size I get from scanning negs at 4800dpi (and 12k x 18k @ 9600dpi). If I scan at 300dpi, image quality is okay, but the actual size is tiny (200 x 300 or so).


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## Josh66 (Jul 26, 2009)

I have a plustek OpticFilm 7300.

I think it does 7200ppi, more (can't remember what) with hardware interpolation.

Maybe I'll try that next time - higher ppi, smaller size.  I didn't think there was really a difference though.


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## astrostu (Jul 26, 2009)

I usually scan at 300 ppi, but lately I've been scanning at 600 ppi - you can always down-sample later.


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## DSPhotography (Jul 26, 2009)

O|||||||O said:


> I have a plustek OpticFilm 7300.
> 
> I think it does 7200ppi, more (can't remember what) with hardware interpolation.
> 
> Maybe I'll try that next time - higher ppi, smaller size.  I didn't think there was really a difference though.



I guess that's where our scanners differ. I can only adjust the dpi resolution, so I couldn't do a 300dpi but have it a 6000 x 9000 image.

I stick with 480dpi because it gives me a REALLY large image file that allows some very fine tune dust (and the occasional cat hair) removal. Once I get the dust, if any, out of the image, I'll resize the image by 50% while maintaining the original resolution of 4800dpi (it's one of the resizing options in CS4 just can't remember off he top of my head), which gives me an image size that's more "workable" without losing ANY quality. 

Example:






Scanned @ 4800 dpi. Resized by 50%, then 25%
Image went from 9000px by 6000px to appx. 1000 by 700 without any compression or quality loss.


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## flea77 (Jul 27, 2009)

O|||||||O said:


> What resolution do you guys scan at?
> 
> I usually scan at 6000x9000 pixels (20x30" at 300dpi).



Funny you should mention this because one of my scanners is the 7200 and I was in the same boat a while back trying to find the right resolution. Here is what I came up with.....

35mm film has a native resolution measured in LPMM of resolving power. Each film is different. I shoot a lot of Ilford Delta 100 Pro which is supposedly extremely fine in detail, it has a LPMM of 160. This translates out to 4064 lines per inch, and given the 35mm frame size of .9448819 inches by 1.417323 inches that gives me a maximum resolving resolution of 3840x5443. That translates into scanning at 3600dpi (3402x5102) and with standard digital printers gives you a maximum print size of about 11x14 with no enlargement, pixel to pixel.

This is all theoretical maximums (which I use as law so that my scanning can not possibly degrade the image). Your lens and any camera vibration at all WILL cause the resolving power to be lower than this maximum. Scanning at anything above 3600dpi is, according to my math, a complete waste of time and hard drive space. Think of it this way, you can scan a 4x6 print at 10,000dpi, but if you try to print it at 24"x36" it will still look like garbage because the 4x6 was printed at 300dpi so anything above the 1200x1800 it was printed at will not exist.

One note, this assumes you are scanning to a TIFF and not a JPEG as the latter is so compressed it is not even funny.

This means you can scan to a resolution equal to about a 1Ds III (21.1MP), and if you scan to TIFF you will far exceed the 1Ds III in color resolution (film=21.1MP, 1Ds III=5.275MP).

Hope this helps!

Allan

PS. You can also use that 160LPMM to calculate maximum print sizes and scan resolutions for other formats besides 35mm, for example, medium format 6x9=9600x14400(138MP), large format 4x5=21770x27213(592MP).


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## DSPhotography (Jul 27, 2009)

flea77 said:


> O|||||||O said:
> 
> 
> > What resolution do you guys scan at?
> ...



Thanks for your post man. I too shoot Ilford Delta 100 primarily, so your info was perfect for me. I've always stuck with 4800dpi (yes, .tiff, only time they become jpeg is for the web and I still keep the original as a .tif). Takes my scanner about 3-5 minutes per frame at that res. I've tried 9600 but there wasn't any noticeable improvement and it took 10 minutes per frame lol. I might try the 3600dpi just to see if it really i just as good as 4800.

Thanks again =)


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## djacobox372 (Aug 4, 2009)

3200dpi for me, anything more then that and I can't see the difference.


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## bobzam (Jan 10, 2010)

I will ask here on this thread. I just got a Epson V600 and experimenting with some slides to get the size and specs for putting them on DVD for TV viewing.

What Color bit? Resolution? Output Target size?

I have been pleased with a few runs and projecting them on my 52 inch HDTV.

But I am looking for efficiency and to avoid overkill.

I may get a scanner which has a feed as I have a lot of slides I may want to get in digital safekeeping.

Bob


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## astrostu (Jan 10, 2010)

bobzam said:


> What Color bit? Resolution? Output Target size?



Color bit probably means color bit-depth.  Colors are represented by numbers.  They range in value from 0 to a larger number where that larger number is a power of 2.  8-bit would be a range from 0-2^8 (0-256).  16-bit would be 0-2^16 (0-65,536).  That's why in the olden days monitors would display "hundreds" of colors or "thousands" of colors ... 2^32 will be "millions."

But, a color picture is where each pixel is made of a red, green, and blue color (if in RGB color space).  So you have all those gradations for EACH R, G, B.  So your scanner likely has a setting for 24-bit, which would be 8-bit R, G, and B.  48-bit would be 16 in R, G, B.

Resolution is either in pixels per inch or centimeter, or the final output size in pixels.  Likely the former, where your "output target size" is the dimensions of the final image in pixels.


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