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!