<sect3 id="editor-color-auto">
    <sect3info> <title>Auto-Correction Tools</title>

    <abstract>
        <para>
        This tool set provides five automatic correction levels that will improve an image in most cases. Use this tool before going into the more involved manual adjustments.
        </para>
    </abstract>

    </sect3info>

    <title>Introduction</title>
    <anchor id="autocolorcorrectiontool.anchor"/>

    <para>

        The <guilabel>Normalize</guilabel>, <guilabel>Equalize</guilabel>, <guilabel>Auto Levels</guilabel>, and <guilabel>Stretch Contrast</guilabel>
        available from <menuchoice><guilabel>Correct</guilabel><guimenuitem>Auto-Correction</guimenuitem></menuchoice> menu entry menu will attempt to 
        work out the best color levels automatically. You will need to experiment with the effects of these functions to see what works best with your photograph.

        <itemizedlist>

            <listitem>
                <para>
                    <guilabel>Normalize</guilabel>: this method scales brightness values across the selected image so that the darkest 
                    point becomes black, and the brightest point becomes as bright as possible without altering its hue. 
                    This is often a "magic fix" for images that are dim or washed out.

                    <example>
                        <title>Normalize Colors Correction Preview</title>
                        <screenshot><screeninfo>Normalize Colors Correction Preview</screeninfo>
                            <mediaobject><imageobject><imagedata fileref="&path;editor-normalize.png" format="PNG" /> </imageobject></mediaobject>
                        </screenshot>
                    </example>

                </para>
            </listitem>

            <listitem>
                <para>
                    <guilabel>Equalize</guilabel>: this method adjusts the brightness of colors across the selected image so that 
                    the histogram for the Value channel is as flat as possible, that is, so that each possible brightness value appears 
                    at about the same number of pixels as each other value. Sometimes Equalize works wonderfully at enhancing the contrasts of an image. 
                    Other times it gives garbage. It is a very powerful operation, which can either work miracles on an image or destroy it.

                    <example>
                        <title>Equalize Colors Correction Preview</title>
                        <screenshot>
                            <screeninfo>Equalize Colors Correction Preview</screeninfo>
                            <mediaobject><imageobject><imagedata fileref="&path;editor-equalize.png" format="PNG" /></imageobject></mediaobject>
                        </screenshot>
                    </example>

                    </para>
            </listitem>

            <listitem>
                <para>
                    <guilabel>Auto-levels</guilabel>: this method maximizes the tonal range in the Red, Green, and Blue channels. 
                    It determines the image shadow and highlight limit values and adjust the Red, Green, and Blue channels to a full histogram range.

                    <example>
                        <title>Auto Levels Correction Preview</title>
                        <screenshot>
                            <screeninfo>Auto Levels Correction Preview</screeninfo>
                            <mediaobject><imageobject><imagedata fileref="&path;editor-autolevels.png" format="PNG" /></imageobject></mediaobject>
                        </screenshot>
                    </example>

                </para>
            </listitem>

            <listitem>
                <para>
                    <guilabel>Stretch Contrast</guilabel>: this method enhances the contrast and brightness of the RGB values 
                    of an image by stretching the lowest and highest values to their fullest range, adjusting everything in between. 
                    This is noticeable only with washed-out images and can be a good fix-it tool for bad photographs.

                    <example>
                        <title>Stretch Contrast Correction</title>
                        <screenshot>
                            <screeninfo>Stretch Contrast Correction Preview</screeninfo>
                            <mediaobject><imageobject><imagedata fileref="&path;editor-stretchcontrast.png" format="PNG" /></imageobject></mediaobject>
                        </screenshot>
                    </example>
                </para>
            </listitem>

        </itemizedlist>

    </para>

    <para>
        The results of any adjustments you make will not be remembered until you save your photograph.
    </para>

</sect3>

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