Re: [Gimp-user] hard lines gimp

[Steve Kinney <admin pilobilus net>]

On 11/06/2016 02:16 AM, bronxsystem wrote:
> Hey all
> I am new at this very new.
>
> Ive spent over an hour to just draw this shape ive tried different
things but
> how is it so blurry/pixely? how to i make it smooth and sharp?

Since a digital image is made of pixels, making smooth curves in digital
images is not a possible thing, and what appear to be smooth curves and
diagonal lines actually have stair-step edges when you look closely.
This jagged-edge appearance is called aliasing.  Anti-aliasing creates a
better illusion of smoothness by averaging out the colors of foreground
pixels with their background, "as if" one were taking a digital photo of
a real object.  The painting and selection tools in the GIMP use
anti-aliasing by default.

To get the /appearance/ of smooth, sharp edged curves, increase the
resolution of the image:  The more tiny squares one has, the better the
illusion of smoothness.

Resolution is measured in DPI, which means dots (i.e. pixels) per inch.
Many years ago, a typical computer monitor had 72 pixels per inch; for
this reason, the default resolution for digital images in most editors,
scanners, etc. is 72 DPI.  Today monitors have at least 96 DPI
resolution, so 96 DPI is a "better" default for images intended to be
seen on websites, etc.  Printers have much higher resolution, and 300
DPI is normally considered minimum for most images that will be printed,
although pictures that will be used in typical word processor documents
printed in grayscale on plain paper can normally squeak by at 150 DPI -
and their size on disk is about 1/4 that of equivalent 300 DPI images.

Plan ahead:  The first thing to do when making a new image or editing an
existing photo is to determine how large it should be.  For instance, a
picture that will be about 2" x 3" when displayed on a web page or in an
electronic document should be at least 2x96 = 192 pixels by 3x96 = 288
pixels.  If the same image is intended to be printed, it should be at
least 2x300 = 300 pixels by 3x300 = 900 pixels.  Again, if in doubt make
your "original" image larger, because scaling it to a smaller size is
less destructive than blowing it up.  Normally you will want to save
your XCF file at "full size", then scale it down to export a JPG, PNG or
etc. image for display or printing.

If an image might be used for both screen display and print, make it at
300 DPI, and export a scaled down copy for use on websites or etc.;
scaling an image down creates less visual "noise" than scaling an image
up.

The relevant GIMP manual page:

https://docs.gimp.org/en/gimp-image-scale.html

Note:  If you want /real/ sharp edges on curved objects, that's possible
with vector based editors like CAD programs, Inkscape, etc.  Photo
editors work with grids of pixels, but vector editors use mathematical
expressions that describe curves etc. precisely, and the same vector
image looks "right" when rendered at any scale from matchbook cover to
billboard.  That's why frequently re-used images like company logos
should be created with a vector editor; any place you need that image,
just export a copy at the exact scale required.  Vector images are also
used with tools like plotters, CAD/CAM devices, etc. and in silk screen
and offset printing applications.

:o)

Steve