Test Images
The original image is full color 24 bits per pixel and twice the array size.
It is (690,000 bytes).
The Image is composed of 5 different images:
- The sky is from a desert image of Edward's Dry Lake;
- The mountains have a city below them and to the left;
- The green hillside on the left is originally a flat field;
- The trees at the bottom are trees sticking over a house;
- The Hot air balloon is from a mass launching at night.
JPEG--6,086 Bytes
Quality 80 (low)--250 X 225 Pixels.
Note the effects of the JPEG compression.
The square splotchy appearance of the sky.
The bright edges of the clouds.
The blurred edges where the mountains meet the sky.
The light hallow around the balloon.
The striped appearance of the snow against the mountain.
The loss of sharp edges in the trees.
But it's only 6K Bytes !!!
JPEG--15,332 Bytes
Quality 30 (medium low)--250 X 225 Pixels.
The effects of JPEG compression are almost gone.
They are still there if you look closely.
JPEG--27,715 Bytes
Quality 10 (high)--250 X 225 Pixels.
The effects of JPEG compression are basically gone.
It's hard to tell this from the original.
The edges are sharp and clean.
GIF--15,265 Bytes
16 Colors--250 X 225 pixels
No Dithering
The reduction to 16 colors causes a banded effect. 13 colors used.
The snow isn't white.
The balloon isn't colorful anymore.
The hillside on the left has very little green.
The leaves appear splotchy on the trees.
Basically very poor.
GIF--22,058 Bytes
256 Colors--250 X 225 pixels
No Dithering--Standard Pallet
Because we used the standard pallet, only 79 of the 256 possible colors were used. Without dithering,
the color bands and shifts are still apparent.
GIF--27,715 Bytes
256 colors--250 X 225 pixels
Diffusion Dithered--Standard Pallet
There are 94 colors used from the standard pallet.
The color banding is gone. It's replaced by speckles.
The diffusion dithering caused speckles.
Dithering intermixes colors for more apparent colors.
GIF--46,744 Bytes
250 X 225 pixels--256 colors
Diffusion Dithered--Optimized Pallet
250 colors were used because we optimized the pallet.
The dithering is hard to see,
because of the close color similarity (more colors).
Not a bad image. But what a cost.
Almost 50K bytes !!!.
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