Re: save as jpg

Posted by Gwen Barnes on Mar 06, 2008; 4:42pm
URL: http://imagej.273.s1.nabble.com/save-as-jpg-tp3696972p3696989.html

That's the answer I was looking for, thanks!  It might also explain what I
was seeing in the images.  They're grayscale initially, but I annotate them
with colored lines.  It seemed to be the colored lines that were getting
blurred, but the rest of the image seemed unaffected.  For now I simply
won't use save as jpeg in imagej.  However, I would use a "turn off sub
sampling" option such as you mention, if one were added.

-Gwen

On Thu, Mar 6, 2008 at 8:18 AM, Jon Harman <[hidden email]>
wrote:

> Hi,
>
> Are your images in color?
>
> ImageJ uses the Sun jpeg writer with the default settings.  By default
> these settings subsample colors, but not brightness.  This results in
> significant degradation of the colors in an image, but to human eyes in
> a color photo this is not noticeable.
>
> For color medical images I would think this is not a good idea.
>
> Jpeg may not be the best image compression algorithm, but its use on the
> web is overwhelming.
>
> Maybe a solution is to add a choice to the jpeg I/O options:
> Disable color subsampling.
>
> For ImageJ I think compression size is less important than quality.  So
> I would recommend that the default for ImageJ should be to not do
> subsampling.
>
>
> Jon
>
> Gwen Barnes wrote:
> > Hi,
> >
> > I'm have a question about saving images as jpg.  I set the quality to
> 100
> > under "edit, options, I/O options", but still, when I save a tiff as a
> jpeg,
> > I end up with jpeg artifacts.  If I use other programs, and save the
> same
> > tiff as a quality 100 jpg, I don't get the artifacts.  Is there a way to
> > save a full quality jpeg in ImageJ?  Any ideas what I need to do
> > differently?  Thanks.
> >
> > -Gwen
> >
>