Optimization or percentage decrease

[toplisek]

I try to optimize images but need to know if there is a difference between decrease in percentage like 100% to 50% or optimization software based on algorithm for formats JPG, PNG.

An example:
If this is optimization for website design, it can be used optimization software based on algorithm.
If there is only upload on eBay, you can used simply 50% from 100% quality.

Where can be found more information about a difference?

[gwpriester]

Where can be found more information about a difference?

If I understand your question, then the answer is your eyes. Create several copies of an image at different percents and see what you can live it.

Xara's default is 85% for JPEG and this seems to be a good compromise between image quality and file size.

JPEG keeps file sizes low by losing pixels that cannot be seen. This often does little to the visible image but it means if you try to enlarge the image there may be a noticeable loss of image sharpness and quality. This is why it is a good idea to keep the original image.

[toplisek]

Is there any article which explains the difference between software like http://optipng.sourceforge.net/ and percentage. It was a question from education. As I understand software works as mathematical algorithm and percentage work as you told % keeps file sizes low by losing pixels that cannot be seen. If you have 10% decrease image will not be seen in sharp view.

[handrawn]

in xara afaik the percentage refers to the amount of compression [removal of pixel information], where 100 % in no compresiion ie all the information is there

what algorithm is used to sachieve this may depend on the software, but for formats such as JPEG/JPG there are industry standards - here is some technical info:

https://www.tutorialspoint.com/dip/i...ompression.htm

[toplisek]

Thank you for the information.