It's not clear exactly what you're doing, but maybe this will help clarify things for you. JPEG is a lossy format. Any time you save a jpeg file it loses image quality. The effect is cumulative. If you reopen the file, then save it again as jpeg the image gets worse (even if you don't try to compress it further).

The best way to deal with jpeg files is to save a master copy of the original file in a lossless format such as PNG, TIFF or even BMP. Use the master copy to edit and save your changes. When you're finished working with the image, save a final copy in JPEG format as a new file. Never edit the original jpeg file directly, you will never be able to recover the lost image quality.

In reply to Re: permagick jpg compression by hangon
in thread permagick jpg compression by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.