Tag: Linux
OpenHPI bietet kostenlosen Linux-Online-Kurs
Vom 12. bis 26. Februar 2018 bietet das Hasso-Plattner-Institut auf seiner Online-Plattform OpenHPI einen kostenlosen Linux-Kurs in deutscher Sprache an.
PNG-Bilder mit OptiPNG optimieren
Für die Richtigkeit der Inhalte dieses Tutorials gebe ich keinerlei Garantie. Der hier gezeigte Weg ist nicht der einzige um ein solches System aufzusetzen, es ist lediglich, der, den ich bevorzuge. Was ist OptiPNG OptiPNG ist ein freies Kommandozeilenprogramm, um Grafiken im PNG-Format effizient zu komprimieren. Außerdem kann es die Integrität von PNG-Dateien prüfen, Metadaten […]
wrjpgcom
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wrjpgcom inserts a textual comment in a JPEG file. You can add to or replace any existing comment(s). Usage: wrjpgcom [switches] [inputfile] Switches (names may be abbreviated): -replace Delete any existing comments -comment "text" Insert comment with given text -cfile name Read comment from named file Notice that you must put quotes around the comment text when you use -comment. If you do not give either -comment or -cfile on the command line, then the comment text is read from standard input. It can be multiple lines, up to 65000 characters total. You must specify an input JPEG file name when supplying comment text from standard input. |
tjbench
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USAGE: tjbench <Inputfile (BMP|PPM)> <Quality> [options] tjbench <Inputfile (JPG)> [options] Options: -alloc = Dynamically allocate JPEG image buffers -bmp = Generate output images in Windows Bitmap format (default = PPM) -bottomup = Test bottom-up compression/decompression -tile = Test performance of the codec when the image is encoded as separate tiles of varying sizes. -rgb, -bgr, -rgbx, -bgrx, -xbgr, -xrgb = Test the specified color conversion path in the codec (default = BGR) -cmyk = Indirectly test YCCK JPEG compression/decompression (the source and destination bitmaps are still RGB. The conversion is done internally prior to compression or after decompression.) -fastupsample = Use the fastest chrominance upsampling algorithm available in the underlying codec -fastdct = Use the fastest DCT/IDCT algorithms available in the underlying codec -accuratedct = Use the most accurate DCT/IDCT algorithms available in the underlying codec -subsamp <s> = When testing JPEG compression, this option specifies the level of chrominance subsampling to use (<s> = 444, 422, 440, 420, 411, or GRAY). The default is to test Grayscale, 4:2:0, 4:2:2, and 4:4:4 in sequence. -quiet = Output results in tabular rather than verbose format -yuv = Test YUV encoding/decoding functions -yuvpad <p> = If testing YUV encoding/decoding, this specifies the number of bytes to which each row of each plane in the intermediate YUV image is padded (default = 1) -scale M/N = Scale down the width/height of the decompressed JPEG image by a factor of M/N (M/N = 2/1, 15/8, 7/4, 13/8, 3/2, 11/8, 5/4, 9/8, 1/1, 7/8, 3/4, 5/8, 1/2, 3/8, 1/4, or 1/8) -hflip, -vflip, -transpose, -transverse, -rot90, -rot180, -rot270 = Perform the corresponding lossless transform prior to decompression (these options are mutually exclusive) -grayscale = Perform lossless grayscale conversion prior to decompression test (can be combined with the other transforms above) -benchtime <t> = Run each benchmark for at least <t> seconds (default = 5.0) -warmup <w> = Execute each benchmark <w> times to prime the cache before taking performance measurements (default = 1) -componly = Stop after running compression tests. Do not test decompression. NOTE: If the quality is specified as a range (e.g. 90-100), a separate test will be performed for all quality values in the range. |
rdjpgcom
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rdjpgcom displays any textual comments in a JPEG file. Usage: rdjpgcom [switches] [inputfile] Switches (names may be abbreviated): -raw Display non-printable characters in comments (unsafe) -verbose Also display dimensions of JPEG image |
jpegtran
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usage: jpegtran [switches] [inputfile] Switches (names may be abbreviated): -copy none Copy no extra markers from source file -copy comments Copy only comment markers (default) -copy all Copy all extra markers -optimize Optimize Huffman table (smaller file, but slow compression) -progressive Create progressive JPEG file Switches for modifying the image: -crop WxH+X+Y Crop to a rectangular subarea -grayscale Reduce to grayscale (omit color data) -flip [horizontal|vertical] Mirror image (left-right or top-bottom) -perfect Fail if there is non-transformable edge blocks -rotate [90|180|270] Rotate image (degrees clockwise) -transpose Transpose image -transverse Transverse transpose image -trim Drop non-transformable edge blocks Switches for advanced users: -arithmetic Use arithmetic coding -restart N Set restart interval in rows, or in blocks with B -maxmemory N Maximum memory to use (in kbytes) -outfile name Specify name for output file -verbose or -debug Emit debug output -version Print version information and exit Switches for wizards: -scans file Create multi-scan JPEG per script file |
djpeg
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usage: djpeg [switches] [inputfile] Switches (names may be abbreviated): -colors N Reduce image to no more than N colors -fast Fast, low-quality processing -grayscale Force grayscale output -rgb Force RGB output -rgb565 Force RGB565 output -scale M/N Scale output image by fraction M/N, eg, 1/8 -bmp Select BMP output format (Windows style) -gif Select GIF output format -os2 Select BMP output format (OS/2 style) -pnm Select PBMPLUS (PPM/PGM) output format (default) -targa Select Targa output format Switches for advanced users: -dct int Use integer DCT method (default) -dct fast Use fast integer DCT (less accurate) -dct float Use floating-point DCT method -dither fs Use F-S dithering (default) -dither none Don't use dithering in quantization -dither ordered Use ordered dither (medium speed, quality) -map FILE Map to colors used in named image file -nosmooth Don't use high-quality upsampling -onepass Use 1-pass quantization (fast, low quality) -maxmemory N Maximum memory to use (in kbytes) -outfile name Specify name for output file -memsrc Load input file into memory before decompressing -verbose or -debug Emit debug output -version Print version information and exit |
cjpeg
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usage: cjpeg [switches] [inputfile] Switches (names may be abbreviated): -quality N[,...] Compression quality (0..100; 5-95 is useful range) -grayscale Create monochrome JPEG file -rgb Create RGB JPEG file -optimize Optimize Huffman table (smaller file, but slow compression) -progressive Create progressive JPEG file -targa Input file is Targa format (usually not needed) Switches for advanced users: -arithmetic Use arithmetic coding -dct int Use integer DCT method (default) -dct fast Use fast integer DCT (less accurate) -dct float Use floating-point DCT method -restart N Set restart interval in rows, or in blocks with B -smooth N Smooth dithered input (N=1..100 is strength) -maxmemory N Maximum memory to use (in kbytes) -outfile name Specify name for output file -memdst Compress to memory instead of file (useful for benchmarking) -verbose or -debug Emit debug output -version Print version information and exit Switches for wizards: -baseline Force baseline quantization tables -qtables file Use quantization tables given in file -qslots N[,...] Set component quantization tables -sample HxV[,...] Set component sampling factors -scans file Create multi-scan JPEG per script file |
Mozjpeg selber kompilieren
Dieser Artikel erfordert mehr Erfahrung im Umgang mit Linux und ist daher nur für fortgeschrittene Benutzer gedacht. Dieses Tutorial ist als praktischer Leitfaden gedacht und behandelt keine theoretischen Hintergründe. Diese werden in einer Vielzahl von anderen Dokumenten im Internet behandelt. Für die Richtigkeit der Inhalte dieses Tutorials gebe ich keinerlei Garantie. Der hier gezeigte Weg […]