Image histogram

<h2 id="image-manipulation-and-histograms">Image manipulation and histograms</h2>
<p>Image editors typically create a histogram of the image being edited. The histogram plots the number of pixels in the image (vertical axis) with a particular brightness or tonal value (horizontal axis). Algorithms in the digital editor allow the user to visually adjust the brightness value of each pixel and to dynamically display the results as adjustments are made.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> <a href="/facts/Histogram_equalization/vmohr7XK">Histogram equalization</a> is a popular example of these algorithms. Improvements in picture brightness and contrast can thus be obtained.
</p><p>In the field of <a href="/facts/Computer_vision/Tl2Yyk66">computer vision</a>, image histograms can be useful tools for <a href="/facts/Thresholding_(image_processing)/0BuzQHr9">thresholding</a>. Because the information contained in the graph is a representation of pixel distribution as a function of tonal variation, image histograms can be analyzed for peaks and/or valleys. This threshold value can then be used for <a href="/facts/Edge_detection/9VplpIcS">edge detection</a>, <a href="/facts/Image_segmentation/jofAhbxa">image segmentation</a>, and <a href="/facts/Co-occurrence_matrix/gsG7BCRY">co-occurrence matrices</a>.
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<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Color_histogram/IbboXWJV">Color histogram</a>, a multidimensional histogram of the distribution of color in an image</li>
<li><a href="/facts/Curve_(tonality)/KabBAuDF">Curve (tonality)</a></li>
<li><a href="/facts/Histogram_equalization/vmohr7XK">Histogram equalization</a></li>
<li><a href="/facts/Histogram_matching/eURzuh6t">Histogram matching</a></li>
<li><a href="/facts/Image_editing/l5LvzVBa">Image editing</a></li></ul>

<h2 id="external-links">External links</h2>
<ul><li><a href="http://www.cambridgeincolour.com/tutorials/histograms1.htm">CAMERA HISTOGRAMS: TONES & CONTRAST</a> at cambridgeincolour.com</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Ed Sutton. "Histograms and the Zone System". Illustrated Photography. Archived from the original on 2015-02-23. Retrieved 2015-08-31. <a href="https://web.archive.org/web/20150223082314/http://www.illustratedphotography.net/basic-photography/zone-system-histograms" target="_blank">https://web.archive.org/web/20150223082314/http://www.illustratedphotography.net/basic-photography/zone-system-histograms</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Michael Freeman (2005). The Digital SLR Handbook. Ilex. ISBN 1-904705-36-7. <a href="1-904705-36-7" target="_blank">1-904705-36-7</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Todd Vorenkamp. "How to Read Your Camera's Histogram". B&H Explora. Retrieved 2021-05-31. <a href="https://www.bhphotovideo.com/explora/photography/tips-and-solutions/how-read-your-cameras-histogram" target="_blank">https://www.bhphotovideo.com/explora/photography/tips-and-solutions/how-read-your-cameras-histogram</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Ed Sutton. "Histograms and the Zone System". Illustrated Photography. Archived from the original on 2015-02-23. Retrieved 2015-08-31. <a href="https://web.archive.org/web/20150223082314/http://www.illustratedphotography.net/basic-photography/zone-system-histograms" target="_blank">https://web.archive.org/web/20150223082314/http://www.illustratedphotography.net/basic-photography/zone-system-histograms</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>Martin Evening (2007). Adobe Photoshop CS3 for Photographers: A Professional Image Editor's Guide... Focal Press. ISBN 978-0-240-52028-5. <a href="978-0-240-52028-5" target="_blank">978-0-240-52028-5</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
</ol>

Image histogram open-in-new

Image histogram