Re: How to compress large .jpeg images?

On Sunday 29 May 2005 11:15 am, Alan Dayley wrote:
> On Sunday 29 May 2005 10:41 am, Siri Amrit Kaur wrote:
> > The title is pretty self-explanatory, I guess. I have a bunch of .jpeg
> > pictures that are from 1-2 MB in size. I need to compress them for fast
> > loading on webpages and to email them as smaller attachments. I'm
> > having a helluva time understanding the GIMP and I've been googling for
> > hours on this.
> >
> > Can someone please give me a simple step-by-step for this? Thanks!
>
> First I assume when you say "compress" you mean "resize." If that is not
> correct, perhaps you can explain further.
>
> There are many methods to do this, even automated ones. I'll focus on
> your current method in GIMP.
>
> - Open the file (duh)
> - Click in the menus on Image->Scale Image...
> - You see Image Size with connected chain links to the right of the size
> boxes. If they are not connected, click on the links to connect them.
> This maintains the aspect ratio of the image. (ie. Keeps it from getting
> stretched or squashed.)
> - Change the width or height to a value you want. Since they are linked,
> the other dimension will change too.
> - The smaller the dimension value, the smaller the graphic and the smaller
> the file size.
> -- I find that 640x480 is a good size for on screen display and image file
> size is in small multiples of 10K.
> - Save the file using Save As... so you don't wipe out your original.
> - When you save the JPG it will ask what quality you want. This is the
> JPG compression ratio expressed as a percent. The default of 85 is a
> good balance between file size and quality. Decrease the number for less
> quality (ie. more grainy) and a smaller file size. I don't like to go
> below 75 and usually leave it at 85.
>
> Is that what you needed?
>
> Alan

Thanks, Alan. That's essentially what I've been doing, but I guess I was
wondering if there's a better way. I need to resize some of the pictures, or
crop them somewhat, but the real problem is simply how big the filesize is
for transmitting them.

For example, the original size is 1.2 MB. If I simply resize it to 640x432,
it's far too tiny to see well. After cropping the original image and saving
at 70% quality, the size is still 170 KB. Saving at lower quality becomes
jagged.

Siri Amrit
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