Compressing/Posting Images.

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GrahameA
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Joined: Thu Mar 10, 2005 4:28 pm
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Compressing/Posting Images.

#1 Post by GrahameA » Tue Aug 26, 2014 9:03 am

Morning All.

A simplistic answer to a question I was asked.
test2.jpg
test2.jpg (61.71 KiB) Viewed 3968 times
Resized JPEG 30% Compression 62kB

The effect of compression on file size.

Uncompressed RAW File 20MB
Original JPEG minimal compression 5MB

Resized JPEG Minimal Compression 369kB
Resized JPEG 30% Compression 62kB
Resized JPEG 50% Compression 47kB
Resized JPEG 30% Compression 32kB
test4.jpg
test4.jpg (31.93 KiB) Viewed 3968 times
Resized JPEG 30% Compression 32kB

JPEG compression loses data - and you cannot get it back. And the more you compress the file the worse it will look and the smaller the file will be. Look at the difference between the top image and the bottom image. The image is slowly losing definition.

Don't save images as JPEGs if you want to maintain file data.
Grahame.
Shoot a Selfbow, embrace Wood Arrows, discover Vintage, be a Trendsetter.

"Unfortunately, the equating of simplicity with truth doesn't often work in real life. It doesn't often work in science, either." Dr Len Fisher.

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greybeard
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Re: Compressing/Posting Images.

#2 Post by greybeard » Wed Apr 15, 2015 12:07 pm

Compressing images from the larger format [16 and 8 megapixels] digital cameras to a file size under 300kb has issues of degraded images as pointed out in the above post.

I knew my el-cheapo 8 megapixel Samsung camera was adjustable with image sizes ranging from 8 down to 1 megapixel.

While I was playing around in the workshop I took this photo using the 1 megapixel setting. Disregarding the subject matter I think the photo quality is acceptable for the web.

The image [1024 x 768] was uploaded without any compression.

This may help those who do not have much in the way of photographic software.
1 Megapixel Camera Setting.JPG
1 Megapixel Camera Setting.JPG (281.12 KiB) Viewed 3893 times
Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

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