File:Lichtenstein img processing test.png

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Lichtenstein_img_processing_test.png ‎(512 × 512 pixels, file size: 357 KB, MIME type: image/png)

Summary

I needed a test image to be used in some examples of image processing. In books and articles, <a href="https://en.wikipedia.org/wiki/Lenna" class="extiw" title="w:Lenna">Lenna</a> is commonly used, but I can't use it on Commons because it is not in the public domain.

I took a look at the featured pictures, and I have decided to use <a href="//commons.wikimedia.org/wiki/File:Lichtenstein.jpg" title="File:Lichtenstein.jpg">Image:Lichtenstein.jpg</a> because it has several details (higher frequencies) in the bottom left and almost no details (lower frequencies) in the top right, plus sharp edges (between the castle and the sky). It's not as pretty as Lenna, but it's a good compromise! Moreover, it was not taken with a digital camera, so it does not show the typical <a href="https://en.wikipedia.org/wiki/Compression_artifact" class="extiw" title="w:Compression artifact">artifacts</a> due to <a href="https://en.wikipedia.org/wiki/Bayer_pattern" class="extiw" title="w:Bayer pattern">Bayer pattern</a>.

Using GIMP, I have cropped the original image in order to have a squared picture, then I have downscaled it to 512x512 pixels using bi-cubic interpolation: this way the smaller image should have all the frequencies and the artifacts of the original JPEG compression should be negligible. I saved it in a lossless PNG to save the higher frequencies that could be removed by a JPEG compression.

Those are the pictures I have created starting from this one:

Licensing

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File history

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Date/TimeThumbnailDimensionsUserComment
current06:22, 12 January 2017Thumbnail for version as of 06:22, 12 January 2017512 × 512 (357 KB)127.0.0.1 (talk)<p>I needed a test image to be used in some examples of image processing. In books and articles, <a href="https://en.wikipedia.org/wiki/Lenna" class="extiw" title="w:Lenna">Lenna</a> is commonly used, but I can't use it on Commons because it is not in the public domain. </p> <p>I took a look at the featured pictures, and I have decided to use <a href="//commons.wikimedia.org/wiki/File:Lichtenstein.jpg" title="File:Lichtenstein.jpg">Image:Lichtenstein.jpg</a> because it has several details (higher frequencies) in the bottom left and almost no details (lower frequencies) in the top right, plus sharp edges (between the castle and the sky). It's not as pretty as Lenna, but it's a good compromise! Moreover, it was not taken with a digital camera, so it does not show the typical <a href="https://en.wikipedia.org/wiki/Compression_artifact" class="extiw" title="w:Compression artifact">artifacts</a> due to <a href="https://en.wikipedia.org/wiki/Bayer_pattern" class="extiw" title="w:Bayer pattern">Bayer pattern</a>. </p> <p>Using GIMP, I have cropped the original image in order to have a squared picture, then I have downscaled it to 512x512 pixels using bi-cubic interpolation: this way the smaller image should have all the frequencies and the artifacts of the original JPEG compression should be negligible. I saved it in a lossless PNG to save the higher frequencies that could be removed by a JPEG compression. </p> <p>Those are the pictures I have created starting from this one: </p> <ul class="gallery mw-gallery-traditional"> <li class="gallerybox" style="width: 155px"><div style="width: 155px"> <div class="thumb" style="width: 150px;"><div style="margin:15px auto;"><a href="//commons.wikimedia.org/wiki/File:Lichtenstein_jpeg_difference.png" class="image"><img alt="Lichtenstein jpeg difference.png" src="https://upload.wikimedia.org/wikipedia/commons/thumb/f/ff/Lichtenstein_jpeg_difference.png/120px-Lichtenstein_jpeg_difference.png" width="120" height="120" srcset="https://upload.wikimedia.org/wikipedia/commons/thumb/f/ff/Lichtenstein_jpeg_difference.png/180px-Lichtenstein_jpeg_difference.png 1.5x, https://upload.wikimedia.org/wikipedia/commons/thumb/f/ff/Lichtenstein_jpeg_difference.png/240px-Lichtenstein_jpeg_difference.png 2x" data-file-width="512" data-file-height="512"></a></div></div> <div class="gallerytext"> </div> </div></li> <li class="gallerybox" style="width: 155px"><div style="width: 155px"> <div class="thumb" style="width: 150px;"><div style="margin:15px auto;"><a href="//commons.wikimedia.org/wiki/File:Lichtenstein_jpeg2000_difference.png" class="image"><img alt="Lichtenstein jpeg2000 difference.png" src="https://upload.wikimedia.org/wikipedia/commons/thumb/6/66/Lichtenstein_jpeg2000_difference.png/120px-Lichtenstein_jpeg2000_difference.png" width="120" height="120" srcset="https://upload.wikimedia.org/wikipedia/commons/thumb/6/66/Lichtenstein_jpeg2000_difference.png/180px-Lichtenstein_jpeg2000_difference.png 1.5x, https://upload.wikimedia.org/wikipedia/commons/thumb/6/66/Lichtenstein_jpeg2000_difference.png/240px-Lichtenstein_jpeg2000_difference.png 2x" data-file-width="512" data-file-height="512"></a></div></div> <div class="gallerytext"> </div> </div></li> <li class="gallerybox" style="width: 155px"><div style="width: 155px"> <div class="thumb" style="width: 150px;"><div style="margin:15px auto;"><a href="//commons.wikimedia.org/wiki/File:Jpeg2000_2-level_wavelet_transform-lichtenstein.png" class="image"><img alt="Jpeg2000 2-level wavelet transform-lichtenstein.png" src="https://upload.wikimedia.org/wikipedia/commons/thumb/e/e0/Jpeg2000_2-level_wavelet_transform-lichtenstein.png/120px-Jpeg2000_2-level_wavelet_transform-lichtenstein.png" width="120" height="120" srcset="https://upload.wikimedia.org/wikipedia/commons/thumb/e/e0/Jpeg2000_2-level_wavelet_transform-lichtenstein.png/180px-Jpeg2000_2-level_wavelet_transform-lichtenstein.png 1.5x, https://upload.wikimedia.org/wikipedia/commons/thumb/e/e0/Jpeg2000_2-level_wavelet_transform-lichtenstein.png/240px-Jpeg2000_2-level_wavelet_transform-lichtenstein.png 2x" data-file-width="512" data-file-height="512"></a></div></div> <div class="gallerytext"> </div> </div></li> <li class="gallerybox" style="width: 155px"><div style="width: 155px"> <div class="thumb" style="width: 150px;"><div style="margin:51px auto;"><a href="//commons.wikimedia.org/wiki/File:Lichtenstein_bitplanes.png" class="image"><img alt="Lichtenstein bitplanes.png" src="https://upload.wikimedia.org/wikipedia/commons/thumb/4/48/Lichtenstein_bitplanes.png/120px-Lichtenstein_bitplanes.png" width="120" height="48" srcset="https://upload.wikimedia.org/wikipedia/commons/thumb/4/48/Lichtenstein_bitplanes.png/180px-Lichtenstein_bitplanes.png 1.5x, https://upload.wikimedia.org/wikipedia/commons/thumb/4/48/Lichtenstein_bitplanes.png/240px-Lichtenstein_bitplanes.png 2x" data-file-width="1330" data-file-height="536"></a></div></div> <div class="gallerytext"> </div> </div></li> </ul>
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