new ascii site

Waow... an new site with ONLY ASCii/ANSi is on the way... (ans -> jpg)
this would be my first site, as am always been working with BBS:ing (and
still do)

Well, the site will be online soon...

JPEG is a format for photos, not text! Use GIF for your ANSI's!

<lecture title="aardvarko's images lecture" author="aardvarko"
e-mail="aardvarko at geocities dot com" date="march 30, 1998" url="
http://www.geocities.com/SiliconValley/Lab/2672/ "
urlparams="not_finished, personal_page">

Aardy's Images Lecture is divided into two parts: editing formats and
publication formats. Editing formats are file types where quality is
king; whatever file sizes your equipment will handle are great, but for
most purposes you shouldn't upload them to Usenet newsgroups.
alt.binaries.clip-art is an exception. Publication formats are optimized
for fast downloads, usually discarding some image information in the
process. For all editing, it works best to (surprisingly) use an editing
format, then when you're all done convert it to a publication format.


Editing Formats:


TIFF is a format typically used for high-end publishing. However, it's a
messy and complicated format with lots of potential incompatibilities...
It can be compressed in several ways... Packbits, an obsolete format
that uses run-length compression, or LZW, which uses string-based
compression. You can also save TIFF's as Uncompressed. For most
situations, not a good format for Usenet... occasionally acceptable for
downloads. Be careful, though, because Macs and PCs have a different way
of writing TIFFs. The two major browsers (as of the date I last edited
this) do _not_ support TIFF.

BMP is an uncompressed format, with the exception of RLE encoding -
however, RLE does not reduce file size much. It's also not supported by
many applications. Try other compression formats that use codecs such as
LZW for greater compression. For the purposes of Usenet and the
Internet, BMP's are garbage. Macs and Unix systems basically can't read
them, and since they have no or very little compression whatsoever, they
take longer than forever to download. If for some reason you have a true
color image that you don't want to convert to PNG or TIFF, yet maintain
quality, you _could_ use this format on _your own computer_... but don't
even think about uploading it.

PNG is a format that's very similar to a TIFF saved with LZW. However,
it also allows an alpha channel (read: 256 levels of transparency, which
makes edges look _very_ smooth) and very nice interlacing ... but not
much supports it yet. For now, stick with GIF or JPEG for the Web or
Usenet.

PSD is Photoshop's native format. If you are editing an image in
Photoshop and you aren't ready to convert it to a Publication format,
save it as this format. It preserves layers, transparency, printer
settings and some other Photoshop-specific stuff.


Publication Formats:


GIF is a file format for crisp, line art images that either have lots of
solid color or edges that you don't want messed up. (Like text.) It is
not a good format for photographs. GIF89a also supports animation and
transparency. If you are converting a high or true color screenshot to
GIF, in most cases, don't dither it. (In Paint Shop Pro, select Nearest
Color.)  A note: Some programs, such as Fractint (a fractal program)
save special blocks in a GIF file. If you import a Fractint GIF and save
it again, in most applications this discards Fractint's special block.

JPEG is a file format for photography. It'll make the photo of your cat
Muffy look nifty for a lot less disk space then most other formats.
However, it adds compression "artifacts" to images with crisp edges.
(Like most screenshots.) If you are converting a dithered image to JPEG,
pull the following filters on it to make it look nice: Guassian Blur (or
Blur More) , then an Unsharpen Mask. (Play with the clipping and
percentage settings for best results.) Better yet, don't convert a
dithered image to JPEG. Find the source (24-bit or True Color) image and
directly convert it to JPEG.


Terms:


Lossy - Removes some image data in exchange of file size.

Lossless - Does not alter the content of the image. However, in most
(not all) cases lossless formats take up more space then lossy ones.

Run-length encoding - Takes all of the pixels in a row and writes them
more compactly.

For example, this would compress well with RLE (if it were an image)

xxxxxxxxxxxxxxddddddddddddddddddddddddddddddd
xxxxxxxdddddddddddddddddddddddddddddddddddddd

This would not:

xdxdxdxdxdxdxdxdxdxdxdxdxdxdxdxdxdxdxdxdxdxdx

Neither would this:

xjhsdfiudsmnjcnisouwemdkjhfkncnkshsojdkndkjkd

Symbol-based encoding - Takes patterns of pixels and writes them more
compactly.

This would compress well:

xxxxxxxxxxxxxxddddddddddddddddddddddddddddddd
xxxxxxxdddddddddddddddddddddddddddddddddddddd

This would too:

xdxdxdxdxdxdxdxdxdxdxdxdxdxdxdxdxdxdxdxdxdxdx

This might compress better then RLE, but still not very well.

xjhsdfiudsmnjcnisouwemdkjhfkncnkshsojdkndkjkd


Dithering - Taking pixels of different colors and combining them with a
pattern to simulate a different color.

This is the target "color":

iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii

However, say that the application could only use these colors:

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
............................................

This might be what dithering would produce.

.@.@.@.@.@.@.@.@.@.@.@.@.@.@.@.@.@.@.@.@.@.@

From a distance, it looks substantially closer to the target then either
of the two colors alone.

However, you lose image data.

There are three typical dithering types; Solid (also known as Nearest
Color, or None ; good for screenshots) , Error Diffusion (good for
photographic images, although they shouldn't be stored in a format that
needs dithering anyways) and Pattern (good for using with LZW or other
symbol-based encoders) .

However, there are better methods of decreasing color depth available in
some special programs. Check http://www.boxtopsoft.com for one.

PSP - Paint Shop Pro. Popular image editor made by JASC Inc. Get it at
http://www.jasc.com .

True color - 24-bit color.

High color - 16-bit color. Unusual format in images.

JPEG - Joint Photographic Experts Group. Also the name of a popular
photographic codec that they created. Excellent for photographs (big
surprise there) but not so good for images with sharp areas. If
sharpness is unnecesary, blurring the image will make it compress better
with JPEG. Or, try this for images with some sharpness.

1. Select the area that you want to preserve the sharpness of.

2. Select Inverse Selection. (In Photoshop, Select / Invert)

3. You may want to feather the selection. This is not necessary,
however. (In Photoshop, Select / Feather . Values of about 5-10 are good
for most images.)

4. Blur it. (In Photoshop, Filters / Blur / Gaussian Blur . Try about 3;
you may want to try different settings. In PSP, Images / Standard
Filters / Blur . )



Links:

http://www.boutell.com/faq/
http://www.servtech.com/public/dougg/graphics/index.html
http://www.webreference.com/dev/graphics/
http://ppewww.ph.gla.ac.uk/~flavell/www/palette.html
http://the-light.com/netcol.html
http://www.faqs.org/faqs/jpeg-faq/
http://www.inforamp.net/~poynton/Poynton-colour.html
http://www.photo.net/philg/how-to-scan-photos.html
http://www.cyberramp.net/~fulton/scans.html

http://www.adobe.com/studio/tipstechniques/GIFJPGchart/main.html

Visually compares how different images compress as GIF or JPEG. Check it
out!

http://www.digfrontiers.com

Has a number of compression utilities for greatly reducing file sizes,
using a patented algorithm. Although they are commercial software, free
trial versions are downloadable. There are versions for GIF, JPEG and
GIF animations.

http://www.ulead.com

Has several graphics utilities, including the SmartSaver suite for
reducing file sizes and GIF Animator for creating animated GIF's. (Never
would've guessed... :)



Thanks to Lars Marius Garshol, Erik Seaberg, Damien M. Jones, Veronica
Karlsson, Niklas Totterman and Tom Lane for modifications to Aardy's
Images Lecture.


</lecture>

--

     OoO<  aardvarko at geocities dot com      icq 8435513  >OoO
     " "   http://www.geocities.com/SiliconValley/Lab/2672   " "

--

Mikke wrote in message <01bd5cd4$a2dc2340$eb63dcc1@son>...
>Waow... an new site with ONLY ASCii/ANSi is on the way... (ans -> jpg)
>this would be my first site, as am always been working with BBS:ing
(and
>still do)
>
>Well, the site will be online soon...