What does OPTIMIZATION do for the IrfanView JPEG lossless transformation plugin?

What does the IrfanView lossless JPEG rotation plugin "optimization" actually do?

When I rotate a JPG digital photograph using the IrfanView "Options -> JPEG Lossless Operations" plugin, one of the options is to "Optimize JPG file".

The IrfanView 3.98 help doesn't explain what it means to "Optimize the JPEG file".

Does anyone know what this "optimization" setting actually does? Should we leave it checked or unchecked?

Joy found these unused words:

What does the IrfanView lossless JPEG rotation plugin "optimization" actually do?

When I rotate a JPG digital photograph using the IrfanView "Options -> JPEG Lossless Operations" plugin, one of the options is to "Optimize JPG file".
The IrfanView 3.98 help doesn't explain what it means to "Optimize the JPEG file".

Does anyone know what this "optimization" setting actually does? Should we leave it checked or unchecked?

Perhaps ask the programmer, or an Irfanview /generic group.

PS does its 'own' thing.

Joy wrote:

What does the IrfanView lossless JPEG rotation plugin "optimization" actually do?

When I rotate a JPG digital photograph using the IrfanView "Options -> JPEG Lossless Operations" plugin, one of the options is to "Optimize JPG file".
The IrfanView 3.98 help doesn't explain what it means to "Optimize the JPEG file".

Does anyone know what this "optimization" setting actually does? Should we leave it checked or unchecked?

I can't answer your question, but recommend upgrading to the current (4.0) version of Irfanview. Don't forget to upgrade the plugins at the same time!

On May 18, 10:04 am, Joy wrote:

What does the IrfanView lossless JPEG rotation plugin "optimization" actually do?

When I rotate a JPG digital photograph using the IrfanView "Options -> JPEG Lossless Operations" plugin, one of the options is to "Optimize JPG file".
The IrfanView 3.98 help doesn't explain what it means to "Optimize the JPEG file".

Does anyone know what this "optimization" setting actually does?

Jpeg is a two step algorithm where first step transforms the image into a more easily compressible form and drops visually less important information. Second step (huffman) encodes the remaining information in as few bits as it can.

In Jpeg, the Huffman part can either use a predefined set of tables or try to come up with custom tables based on what will work best for that image. First option is obviously easier to implement and uses less processing power so most implementations just do this due to laziness and cameras do this to save battery.

Irfan view's 'optimization' setting makes it calculate and use custom tables which means better compression at no additional loss of quality.

Should we leave it checked or unchecked?

I think you can use it safely. Some old or badly written applications might not support Jpegs with custom tables but this should be rare.

Sachin Garg [India]
www.sachingarg.com | www.c10n.info