-------- Original Message --------
Subject: Re: formats of map compression
Date: Thu, 22 May 2008 11:43:10 -0500
From: Nat Case <[log in to unmask]>
To: [log in to unmask]
Also depends if ths cartography includes gradations in shading, or
consists of flat colors. If the latter, consider .png format, which is
an indexed-color format similar to the old .gif format, but with better
compression. For flat colors, it avoids the JPEG's tendency to apply
artifacts (swirly blurry distortions). It is not as robust for
photograph or photo-like textures, for which MrSid is preferable, and is
industry-standard for remote sensing, as it is less lossy than JPEG.
You may want to see Derek Tonn's excellent site,
http://www.graphicsoptimization.com/diy/filetypes/jpg.htm for more basic
information on reducing file size.
Good luck!
Nat Case
Hedberg Maps, Minnesota USA
> -------- Original Message --------
> Subject: Re: formats of map compression
> Date: Wed, 21 May 2008 17:19:18 -0700
> From: Matt Fox <[log in to unmask]>
> To: [log in to unmask], [log in to unmask]
>
>
>
> Depends on why you are compressing the maps. For archiving you should
> use TIF (Big files but no loss in quality).
>
> If you want to server them over internet, then you will need some kind
> of lossy compression. Simplest is probably JPG. Pretty sure Mr. Sid
> costs money to use. JPG2000 is not widely used.
>
> Matt
>
>
>
> 2008/5/21 Maps-L Moderator <[log in to unmask]>:
>> -------- Original Message --------
>> Subject: formats of map compression
>> Date: Wed, 21 May 2008 19:41:59 +0300
>> From: Linda Akmentiża <[log in to unmask]>
>> To: <[log in to unmask]>
>>
>>
>>
>> Dear Colleagues!
>>
>>
>> The matter of my inquest is formats of map compression.
>>
>>
>> The Department of Cartographic Materials of National Library of Latvia
>> have started a Digital Map Project. What kind of formats have You used
>> creating datafiles - MrSid or JPEG2000, or someone else?
>>
>>
>> What are Your thoughts regarding this matter?
>>
>> Thank You for sharing Your experience,
>>
>>
>>
>> map librarian,
>>
>> Linda Akmentina.
--
Nat Case
Hedberg Maps, Inc
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