Question about printing maps?

[samkatz]

I'm not sure if this is the right forum for this, as it's not exactly a mapping question.

I found this online map of Newark, DE, circa 1878 and thought it would look nice on my wall (I'm from Newark).

map-newark-1878-beers.jpg

I decided it would look better as two separate maps, so I messed with them in photoshop to make the following two images.

The issue: each of these files about 36"x24" at 72 ppi, the resolution of the original, but I realize that this is sort of a low resolution for printing. In photoshop, I set them both to 300 without changing the size. That doesn't really make sense to me, but photoshop let me do it, so I don't know what exactly it did to the images.

When I zoom way in on the computer to make it about 36x24, it looks good (i.e., not blurry), but I don't know if this will translate to a printed page.

If anyone who knows what to look for could look at these images and tell me if I should have them printed in that size, please let me know. If you wouldn't advise me to do that, what are my other options?

Also, anyone know of a high-res version of this map? (I figure it couldn't hurt to ask.)

[samkatz]

Oops, my other maps aren't uploading for some reason.

EDIT: They are too big. Here are links to them. Let me know if there are issues viewing them.

https://drive.google.com/file/d/0B1R...ew?usp=sharing

https://drive.google.com/file/d/0B1R...ew?usp=sharing

[johnvanvliet]

if all you want is a 8.5x11 in ( standard paper)
these very tiny images would work
but i would leave at least 2 to 3 inches border

this image
https://drive.google.com/file/d/0B1R...UzMk1SZWM/view
is only a very small image ( 1065 x 710 pixels )
SMALLER that a modern LCD monitor ( 1920 x 1080 )

most printers default to 300 dots per inch ( dpi ot ppi )
so at the default settings for any home printer this image will print at

3.55 INCHES!!!
X
2.36 INCHES

if you REALLY want a poster size print 36 in x 24 in
you will need a image at the LOW !!! resolution of 300 dpi that would be a image that is

10800 x 7200
that will SHOW pixels
so you really would want a image that is at least 600 dpi for printing a poster ( 21600 x 14400 )

or for a REALLY GOOD quality image you will want 1200 pixels per inch ( Poster image 43200 x 28800 pixels )

[samkatz]

I think Google is compressing the image. The one saved to my hard drive is 10800 x 7200. Could you try downloading it? It's 300 ppi, but I just told photoshop to make it that way from a 72ppi image that was 2592 x 1728. My question is whether the quality has actually improved or if the image (the 300 ppi one) will print blurry.

[johnvanvliet]

I think Google is compressing the image

if by compressed you mean they used an algorithm like "zip","rar","bz2","xz" to losslessy reduce the physical space on the google servers then yes

but if you mean they shrank the size
NO

When I zoom way in on the computer to make it about 36x24, it looks good (i.e., not blurry), but I don't know if this will translate to a printed page.

you can NOT resize a image by zooming into the image

and by "not blurry " you mean you saw the individual SQUARE pixels
like in this screenshot

the image on the right is a zoom ( 800% )

all that "noise" around the letters in the JPG image format lossy compression
it ADDS "BAD" data to the image in the form of these artifacts
jpg is not a good format

you will want to remove that blocky jpg artifacts before printing
a poster size image of this small 2799 x 3075 image will REALLY make that noise stand out

as in this artifact cleaned up image a 800% zoom in ( NOT a larger image )


think of "zooming in" as using a Magnifying glass

It's 300 ppi, but I just told photoshop to make it that way from a 72ppi image that was 2592 x 1728

then it will be blurry from the cubic upscale
you NEED TO START with a big image

the image in the first post will make a decent 8x10 inch print
but NOT a 36 x 24 inch print
http://www.cartographersguild.com/at...chmentid=73326

[samkatz]

Alright, thanks. That's pretty much what I thought, but I was hoping someone would tell me different.

A follow-up question about scanning: If I am able to find a hard copy of this or a similar map, and I can get permission to scan it in higher resolution, how should I do it?

[Midgardsormr]

You might be able to convert that map to vectors, which would free you from concerns about resolution. It's fairly simple line-work, although some of it is fine enough that it might take several tries to get a good trace. Vector Magic is an online tracer that is actually a little bit better than the one in Illustrator, in my opinion. http://vectormagic.com/home

If I recall correctly, it doesn't have very many controls, though, so if it doesn't work to high enough quality you might have to find a different tracer. I wouldn't bother trying to get the paper texture in the trace. You can always have the map printed on speckled paper to restore that look. The watercolor bleeds will also probably cause problems. Depending on how much work you want to put into it and how much fidelity you want the print to have, you can likely touch those up. It might be necessary to trace different parts of the image with different settings to get the best results.

[johnvanvliet]

inkscape is free
BUT
you have to remove that jpg artifacts FIRST

- they are really bad on this image
i used this command in the example
-- the terminal version of gmic

gmic map-newark-1878-beers.jpg  -gimp_bilateral 10,5,8,0,0,24,0 -o map-newark-1878-beersClean.png

[samkatz]

Thank you both for the tips. It turns out my school library has a hard copy, so I may be able to circumvent the process of improving the resolution of these images. But if for some reason I'm not allowed to scan it, I will try out the tracers you suggested.

[johnvanvliet]

there are a few tricks to upscalling and not causing it to get blurry
here is a cleaned up copy that is 20000 x 22425 ( 26 meg)
this should print well , but you will be able to see the original pixels as a box of 10 px

-- i will leave it on my g-drive for a few days
https://drive.google.com/file/d/0B6Z...ew?usp=sharing