[projectaon] Re: Voyage of the Moonsone Illustrations
- From: Jonathan Blake <jonathan.blake@xxxxxxxxxxxxxx>
- To: projectaon@xxxxxxxxxxxxx
- Date: Mon, 18 May 2009 10:43:18 -0700
On Mon, May 18, 2009 at 8:34 AM, Jonathan Blake
<jonathan.blake@xxxxxxxxxxxxxx> wrote:
> For future reference, it would be best to use 300dpi at least (600dpi
> has worked best for me). 200dpi limits us to offering printable
> versions at 150dpi, which is great, but 300dpi would be even better.
For those of you wondering why I say this, one of my steps in cleaning
these up is to reduce the resolution. At full scanned resolution, the
image looks like... well, a scanned image. Reducing the resolution
also reduces the noise making it look cleaner, in this case, more like
a printed black and white illustration.
On top of that, we can always reduce resolution, but it's impossible
to increase resolution and get something usable. I like some wiggle
room to know that I have more image information than I will need in
the finished product.
And yes, I'll start cleaning these up. I'm happy that we have the
chance to do so. :)
P.S. For the sake of the curious, here's an outline of what I do to
clean the scanned images:
1) Drop the color depth to black and white (adjusting the threshold to
reduce noise and preserve image information).
2) Crop the scan closely around the edges of the illustration, but not exactly.
3) Measure how far out of vertical the illustration is using the
illustration borders when available.
4) Rotate to compensate.
5) Increase color depth to 8-bit grayscale.
6) Measure how vertically skewed the image is.
7) Skew to compensate.
8) Redraw the borders to make them exactly straight. (This step takes
the longest by far. I take the time because the human eye easily spots
lines that aren't straight when they should be. Straight borders make
a huge difference in the perceived quality of the finished product.
There are lots of shortcuts that I've learned over the years to speed
up this step, but it almost never takes less than 10 minutes.)
8) Remove any noise (i.e. stray pixels) around the edges of the illustration.
9) Crop the image to fit exactly the edges of the illustration.
10) Save a full resolution TIFF copy of the the cleaned up illustration.
11) Drop the resolution to 72dpi for web images (other resolutions can
be used for print).
12) Scale the image down (386 pixels wide for main illustrations; no
more than 150 pixels high for minor illustrations, padding to 386
pixels wide). Up to this step, the illustration still looks rather
bad. Rescaling is the secret sauce that covers most of the sins
introduced by scanning the image.
13) Save a TIFF copy of the scaled illustration.
14) In the case of web images, export the image as GIF with a reduced
color palette to reduce image size.
15) Covert to PNG using pngout.
Maps are another story because my scanner isn't big enough to scan it
all at once and because I have to scan the text separately (it's on a
celluloid overlay). I have to marry the four images and adjust color
contrast/saturation. Where the two halves meet, I have to adjust the
color because they never exactly match. Maps represent about two hours
of work (a lot of it spent waiting for my poor computer to manipulate
the high resolution images that I use).
I guess now I can rest easy in case I'm hit by a bus that my
techniques are no longer a trade secret. :)
--
Jon
~~~~~~
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