Requested Batch Alternative to Jpeg

[hiker_jon]

Hi,

It would be nice if Irfanview provided a better alternative to the jpeg file format in the batch conversion routines. For instance jpeg2000. Maybe a better alternative file format already exists in Irfanview, if so I apologize and would like to know what it is. I am looking for a format that provides better image quality than jpeg at the same output file size.

[Sjef]

A bmp file of 10 MB when converted to jpeg2000 will take 860 Kb. The same bmp will take about 425 Kb (compressed at 80 on a scale of 100).
The same bmp will take about 2 MB (compressed at 100 on a scale of 100, so no compression). You could zip bmp (best quality) but this takes broadly 8 MB. Conclusion: a big image, let's say a 10 Megapixel digital foto could best JPG-compressed at 90 on a scale of 100 as a compromis between less data and good quality. It is not sure at all Jpeg2000 will run through the future as the final solution and IV users must buy the LuraWave plugin. I suppose that's no option eighter.

[j7n]

An important disadvantage of JPEG2000 is its slow speed. Any quality gains from this format IMHO are insignificant today.

The same bmp will take about 2 MB (compressed at 100 on a scale of 100, so no compression).

JPEG at quality 100 is not lossless if that's what you wanted to say.

You could zip bmp (best quality) but this takes broadly 8 MB.

PNG and RAR/multimedia format will be better than Zip for photographic pictures since both formats include prediction filters along with regular compression.

[Sam_Zen]

Choosing for compression is always a choice between remaining quality and a smaller filesize.
I agree with j7n : even quality 100 of JPEG is not lossless. Such a file has 6 times as less bytes than the original.
And the lost bytes can't be recovered by converting to BMP again.

If compression is at stake, I like to propagate the use of the PNG format.
The compression under the same kind of settings may make bigger filesizes, but the quality is somewhat better.

But more useful : It has more levels to choose for the number of colors than JPEG.
Decreasing the number of colors of a picture upto needed, has a direct influence on the outcoming filesize.
Why saving a picture of just black and white in a resolution of 16 million colors ?
With PNG a custom choice is possible, maybe 4 colors is enough.

Another advantage : On can pick a color to be transparent.

[hiker_jon]

I have not used png and will look into it.

On the DPReview news discussion forum there is a thread about Microsoft trying to get JPEG group approval for their own jpg replacement format. Without any other viable replacement for jpg they just might be successful. Too bad, I am not a Microsoft fan.



Jon

[j7n]

Microsoft cannot make all programs capable of processing JPEG files disappear. I find it somehow irrelevant whether M$ will push its own crippled format or not. Nobody has to use this new file type.