----- Original Message -----
From: <[log in to unmask]>


> On 30 Nov 2001, at 11:03, Demetri Kolokotronis wrote:
>
> > I have bmp files I would like to change to jpg to save space. Any
> > disadvantage doing this? Is there a way to change a large number
> > of files at one time? Any reason I could not change back to bmp if
> > want?
> >
> > Demetri Kolokotronis
>
>   JPEG (.jpg) is sort of a family of formats, depending on how much
> detail is allowed to be lost in the compression.  The decompression
> is fast and the loss is often not noticable with the naked eye.  But
> it is there, and there is no guarantee that a .BMP created by
> converting back from .JPG will be *exactly* the same as the original.
>

Detail loss depnds from compression level. JPEG is good for photograps
but works very badly with drawings. 16 color  gif is much smaller than
barely acceptable quality  JPEG. Other compressions in JPEG family are
so newtht there can be compability problems , I cant read JPEG2000
file converted with another codec.

>   [I have an impression that .GIF doesn't lose details on the
> compression, but may be limited to 256 colours in an image, and you
> may lose some colour fidelity achieving that.
>

True. If you need color quality use PNG supported newer browsers.

>   There *is* a compression format for .BMPs called RLE, which doesn't
> lose any detail, but depending on the image the reduction in size may
> be little or none at all.]
>


Application - IrfanView. Can be do batch conversion.

Toomas

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