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Ham Radio 2000.iso
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1996-06-09
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Note - EZ SSTV has a reduced number of
file types for write. It is also missing
options for compression and other ways
of reducing file size.
File Menu
---------
See the "Menus" topic for general information about the menus.
The File menu contains commands to get images in and out of the
system and to exit.
New
---
This creates a new blank image. If you want a different
background color, use the flood fill (spilling paint) can in
the paint tool box.
Open
----
This is used to read an image file into Pasokon TV.
A variety of image formats are supported:
.BMP - Microsoft Windows Bitmap
.HRZ - 1200C version of N9AMR's Hi Res
.JPG - pronounced Jay Peg
.PCX - PC Paintbrush
.PNG - Portable Network Graphics
.TGA - True Vision Targa
.TIF - Tagged Image File Format
These are described in more detail below.
What happened to GIF? See Run Menu help file for details.
Pick a file name from the File Selector and click on OK.
The File Selector is described in its own help file.
Images are automatically scaled to 640 x 480. You can avoid
the scaling and stretching by reading an image directly to the
Clipboard (see Edit menu) then pasting it.
Save
----
This is used to write an image to a disk file. It supports the
same file types as Open, described above.
Type the name in the File Selector and click on OK or press
the Enter key.
Digitize
--------
This is normally used to run an external program which grabs
an image from a TV camera. It performs the actions in the
DIGITIZE command in the PKTV.CFG file. Read the "Configuration
File" and "Run Menu" help files for more details.
The camera icon in the paint tool box is equivalent to this
menu item.
Print
-----
Print the current image on a printer. You must select the
printer type from the Setup menu before using this.
Delete
------
This allows you to delete a file.
Quit
----
This is used to exit from the program.
File Types
----------
A 640 x 480 image with 16 million colors requires almost a
megabyte of memory. Even with Gigabyte disks now under $300,
you probably don't want to use almost a megabyte for each image.
Different file types and options allow you to make space /
time / quality tradeoffs when writing images to disk.
If your primary concern is speed, use the BMP and TGA file
types with 16 million colors. These have a small header and
the rest of the file is the same as the in-memory file format
so it can be read or written very quickly without any
processing of the data.
If you want to preserve image quality, use BMP, TGA, TIF, or
PNG because they don't lose any color or resolution.
JPG allows very substantial compression but you pay for it
in two ways. First, JPG uses "lossy" compression. That means
when you write an image to a file and read it back again the
image will NOT be identical to the original. You won't notice
the difference with natural images. However, it can add
artifacts when images contain computer-generated graphics
with sharp, high contrast edges. It also takes longer to read
and write these files because a lot of computation is
required.
PNG offers "lossless" compression. That means the result of
compressing then decompressing is identical to the original.
There is not much reason to use PCX. This allows only 256
colors and it takes a long time to pick a suitable set of 256
colors based on the particular image contents.
File Save Options
-----------------
These allow you to save disk space by reducing image quality.
320 x 240
When this option is turned on, images are scaled to half
the width and half the size, resulting in a file about
one quarter of the size.
This takes more processing time because the image has to
be scaled down to half size. However, writing only 1/4
of the amount of image data to disk might make up for it.
This does not affect .HRZ files because they are always
256 x 240.
This does not affect files written from the Clipboard
(see Edit Menu description) because they can have
any arbitrary size, even bigger than 640 x 480.
JPEG ...
These allow you to pick a compression level for JPG files.
A smaller file will provide lower quality. The best
quality requires the largest file. The middle choice is
probably a good compromise for most cases.
TGA 32K
When this option is active TGA files are written with
32 thousand colors instead of 16 million. The file
size will be about 2/3 of the normal size.