Myths About Slide Scanning and Negative Scanning: Scanning Is Fast

Myth: Scanning is fast.

The manufacturers of scanning and computer hardware would have you believe that scanning slides and negatives is very fast. At best, we might say that they bend the truth for their own benefit.

Let us examine a specific claim for scanning speed. Nikon advertises the following for the Nikon 5000 ED scanner (the source of this quote is here):

(time to complete preview or scan when no options selected): Preview: 11 seconds Scan*: 20 seconds (time to complete preview or scan when no options are selected)* includes time required to display the scanned image

That sounds pretty good! 20 seconds per image isn't a long time to wait. However, this ignores some very important issues that significantly icrease the time required to actually do the scanning work. Minimally, you will probably use auto focus and ICE (dust and scratch removal) on every scan. Aditionally, every image must be saved to disk. The Nikon times above ignore these critical time consuming components.

Here are our timing results, on a high-end PC using the Nikon 5000 ED scanner to scan Kodak slides and negatives.

Film Type	Activity	1000 PPI	2000 PPI	3000 PPI	4000 PPI
Color 35mm Slide	Preview, without ICE	21.3s	32.0s	33.4s	33.7s
	Scan without ICE	21.4s	34.6s	42.7s	41.3s
	Scan with ICE	24.6s	40.1s	53.1s	54.6s
Color 35mm negative	Preview, without ICE	15.2s	22.7s	24.9s	25.3s
	Scan without ICE	20.2s	31.0s	40.0s	39.8s
	Scan with ICE	25.5s	44.7s	64.0s	64.7s
Testing system and software details: Intel Core 2 Duo Processor, 1 GB RAM, Windows XP, TIFF images are saved to local SATA drives, USB 2.0 connection to scanner, Vuescan version 8.4.53 scanning software, 8 bits per color channel, auto focus, auto exposure, Adobe RGB color space, three scan/preview runs for each data point with average time reported.

As you can see, actual scan time are significantly longer than the 20 seconds quoted by Nikon in their sales literature. Why? Because the Nikon specifications quote an unrealistic scanning environment and software setup that does not include critical items such as high-resolution scans, the use of auto focus and auto exposure, ICE dust and scratch removal, and the time required to save images to disk.

Additionally, there are other significant times that we have not accounted for yet. This includes:

• cleaning the slide/negative prior to scanning. Though you are likely to use ICE dust and scratch removal to avoid many issues with dirty film, you will still want to dust the film using compressed air to remove most dust, dirt and hair from the film. This takes at least a few seconds per slide or negative strip.
• loading the slides/negatives into the scanner. Depending on the scanner and software you are using, loading the film into the scanner and getting the proper alignment and cropping can take from a few seconds to a minute if previews are required to do alignment (e.g., when scanning negative strips with many scanners).
• adjusting the resulting digital image after scanning. Almost every scanned image requires adjustment after scanning. This may take only a few seconds (after opening the file in Photoshop or other editing software) - or much longer for badly exposed, faded, or color shifted images. If you are not very familiar with editing scanned images, this may require significant time.

These activities add from a few seconds to a few minutes to each scan. The "20 seconds per scan" information from Nikon is a misrepresentation of the facts to sway your buying decision. Nikon isn't alone in this approach; every scanner manufacturer has similarly misleading times quoted for their scanners.

So, what does this mean? It means that you can't scan very many images per hour of work. Realistically, with a single scanner and a single computer to do post scan processing, you can scan only a small number of images per hour. Scanning at 4000 PPI, each frame scanned will require the following time:

• 10 seconds to clean film
• 15 seconds to load, align and crop film
• 20 seconds to preview image
• 15 seconds to adjust scanning options after preview
• 60 seconds to scan and save file
• 10 seconds to open file in photo editor
• 60 seconds to edit image
• 10 seconds to save edited image file
• Total: more than 3 minutes per frame, or less than 20 images per hour if you work continuously and keep the computer busy. You are likely to achieve much less than this.

Save to del.icio.us Digg This Story