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Date Posted: 17:49:54 09/11/00 Mon
Author: Michel
Subject: Re: Saved JPeg Smaller than Original
In reply to: Rea Berryman 's message, "Re: Saved JPeg Smaller than Original" on 09:26:03 09/08/00 Fri


Hi Rea,

The jpeg algorithm is very complex, using a mathematical transform to create an image which

loses some color information to reduce the file size. At a "good enough" quality setting,

this degradation may not be noticed. I am not a JPEG expert, so the reason why the image is

larger at a 100% is really related to the "lossy" jpeg algorithm. The JPEG support in

Envision is based on the "Independent JPEG group's" library; it is the same library used by

Delphi 3 and above, and many other graphic packages.

When storing in a database there is a loss of quality too. JPEG is a format ideal when

saving the image once, where it will no longer be modified.

Best regards,

Michel

> Looks like I have a bit to learn about JPeg! With the
> SaveQuality set to 100, the new file is larger than
> the original. What causes this?
>
> Also, does storing a JPeg in a database cause some
> loss of quality?
>
> Thanks,
> Rea
>
>
> >
> > Hi Rea,
> >
> > You can adjust the size of the JPEG size by setting
> > the SaveQuality property of the TJpegGraphic
> property.
> > In the demo, the would be done in the
> > ImageScrollBoxBeforeSave event.
> >
> > Note that resaving a JPEG will lose some quality, as
> > JPEG is a lossy compression algorithm.
> >
> > Best regards,
> >
> > Michel
> >
> > > Using the demo program, I opened a JPeg and then
> > saved
> > > it with a different file name. The new file was
> about
> > > 1/4 the size of the original. How do I save a JPeg
> > > without changing the size of the file?
> > >
> > > Thanks,
> > > Rea

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