Marja-Leena Rathje
Home ::: a scan test

a scan test


#1. Originally scanned at 300 dpi.


#2. Originally scanned at 600 dpi.

My last post on scanning certainly piqued the interest of several readers! I look forward to seeing the results of your play, everyone! Barrett tried it out with his 'cheapo' (his word) scanner and was very disappointed.

I thought I would demonstrate a test I did for myself as much as for Barrett and any readers interested in more on this subject. I did two scans of the same object, enlarged by 200%, varying only the dpi (dots per inch), the first one at 300 dpi and the second one at 600 dpi.

I placed a handy object, a shell about 10 cm or 4 inches in length, on my open scanner and ran the scanner via PhotoShop. Each comes up as a .psd (PhotoShop) file, better than a Tiff for working with initially. The first scan came up at 3.29 MB in size and the second one at 52.6 MB.

For this test, I made no adjustments for colour, levels, contrast or anything else. On each image, I changed the resolution to 72 ppi, and the image width to 500 ppi. The file size on both then became 455K. Then I proceeded to 'save to the web' on each, choosing high quality, 79 (I could have gone higher but this is often the range I normally choose). The result?- both around 48K. The images automatically saved as jpegs. Then I uploaded them to the blog, eager to see if there's any difference. What do you think? Very subtle to my eyes!

So, the point of this very dry demonstration is to show that if your goal is just to put your scanned image on your blog, you do not have to scan at a huge resolution. I find around 300 is very good, and less would work, depending on your scanner quality.

If you plan to print your image, especially very large, then you may wish to use a very high resolution and magnification to get greater detail. For example, one artist friend of mine did a series of scans of leaves at the highest resolution (1200 dpi?) and after much work on the images, printed them something like 90 x 120 cm (3 ft by 4 ft). They were amazing!

For my own digital printmaking on more moderate paper sizes and with a high-end printer, I'm usually satisfied with less resolution, say at 300. Tests and trials are very much a part of the process for me to determine what works best for the image.

I'd love to hear from others who have a lot of scanning experience and have any tips to share, for I'm always learning!

Marja-Leena | 19/07/2008 | 6 comments
themes: Being an Artist, Blogging, Photography, Tools and technology


We need dry demonstrations. The ectasy comes from viewing the end-product. I like the idea of an oyster shell (rich man's food over here) transformed into an object of beauty for all of us. Any moment now I'll espouse democracy! The key piece of advice is opening the scanner through Photoshop and avoiding the Tiff problem. I note that people have apparently been scanning 3D items for ages. Fine. But for me, and some others, it was all new and that's what counts. Thanks for everything.

Barrett, thanks for your generous and funny interpretation! I'm a little sad to say that good software and a good scanner costs, even for this struggling artist! PhotoShop Elements perhaps? As I've said before, I haven't researched other possibilities in all this wonderful technology out there. Judging from your blog that's a passion of yours! Please don't give up trying even with your existing scanner. It's amazing what some people can achieve with little.

I have had a go with some stones - really enjoyed the exercise. I've put the result up on my blog. Don't laugh.

Anna, your scans are great, with those interesting fossils that you've expanded on. No, I did not laugh, just feel tickled to bits that I've inspired you!

300 dpi is the minimum printing standard, so anything that needs to be printed ought to be scanned at 300 dpi or higher. I never had a full grasp of how it worked but I think you only increase the scanned dpi if you're enlarging it (proportionately to the scale of enlargement). I'd have to check my notes.

The 2nd image seems to me a little less sharp!

Erika, yes, that's correct. If I wanted a huge print, the second one would be better. There's a formula I've seen somewhere. As you likely know, it's best to do as much as possible in the scan rather than later compensating in PhotoShop. You think the second image is less sharp? Hmmm, probably the compression doing it. I could show you the original full size scans and you can see the difference in detail there.