Image Edit



C Denning,

Wilmslow,

Cheshire.



Have you ever wished you could combine the individual

pictures you have created and stored on cassette? This is

difficult in Basic as you cannot merge two screens or load

one with OVER on. This progam, Image Edit for the 48K

Spectrum, lets you combine pictures.

  You should be shown a menu. If you want to combine 2, 3

or 4 images, load them into different screens. To combine

more than four images, load them in stages of four, saving

the composite on cassette each time. later, combine the

composite images.

  When you have loaded all the images you want, press S to

start the machine-code program. There are two different

ways of combining images, using the machine code commands

OR or XOR.

  XOR puts the images together in the same way as the Basic

command OVER. Where there is an overlap, a space is made.

OR adds the images completely, leaving the overlap black.

When using the machine-code program, press 1, 2, 3 or 4 to

put an image on the screen. It will be added to what is

already on the screen according to the mode - XOR or OR.

# 8 and 9 put the program in XOR and OR modes respectively.

# 6 returns to the Basic program.

# 0 clears the screen.

  When returning to the Basic program, you will be given

the opportunity of saving the composite or loading more

images.

  It is possible to create some other effects by combina-

tions of the two modes. For example, you can subtract an

image from what is already on the screen by adding it first

in OR mode, then in XOR mode.

  When combining the pictures, colours are ignored as they

would be jumbled when combined. The final image is saved as

black on white.

  [Three final notes from your humble typist. One, the code

is loaded into the printer buffer, so beware if you want to

COPY the resulting screen. Two, I've also provided four

very simple sample screens to play with; I had to test that

the program works, and I might as well leave them in. And

three, if you load a screen saved as SCREEN$ (as these test

screens were, for example), is it loaded _with_ attributes,

which overwrite the start of the next screen. To get around

this, either save only the pixel data of your screens,

using SAVE "name"CODE 16384,6144, or always load them in

ascending order.]