This how-to is tell you how to add a watermark on the image file.
The image file is youtube.jpg, 1024×768.
I would like to add a watermark to the youtube.jpg. The watermark is a small picture.
Install Imagemagick
sudo apt install imagemagick
davidyin@tesing_machine:~$ composite Version: ImageMagick 6.9.7-4 Q16 x86_64 20170114 http://www.imagemagick.org Copyright: © 1999-2017 ImageMagick Studio LLC License: http://www.imagemagick.org/script/license.php Features: Cipher DPC Modules OpenMP Delegates (built-in): bzlib djvu fftw fontconfig freetype jbig jng jpeg lcms lqr ltdl lzma openexr pangocairo png tiff wmf x xml zlib Usage: composite-im6.q16 [options ...] image [options ...] composite [ [options ...] mask ] [options ...] composite Image Settings: -affine matrix affine transform matrix -alpha option on, activate, off, deactivate, set, opaque, copy transparent, extract, background, or shape -authenticate password decipher image with this password -blue-primary point chromaticity blue primary point -channel type apply option to select image channels -colorspace type alternate image colorspace -comment string annotate image with comment -compose operator composite operator -compress type type of pixel compression when writing the image -define format:option define one or more image format options -depth value image depth -density geometry horizontal and vertical density of the image -display server get image or font from this X server -dispose method layer disposal method -dither method apply error diffusion to image -encoding type text encoding type -endian type endianness (MSB or LSB) of the image -filter type use this filter when resizing an image -font name render text with this font -format "string" output formatted image characteristics -gravity type which direction to gravitate towards -green-primary point chromaticity green primary point -interlace type type of image interlacing scheme -interpolate method pixel color interpolation method -label string assign a label to an image -limit type value pixel cache resource limit -matte store matte channel if the image has one -monitor monitor progress -page geometry size and location of an image canvas (setting) -pointsize value font point size -quality value JPEG/MIFF/PNG compression level -quiet suppress all warning messages -red-primary point chromaticity red primary point -regard-warnings pay attention to warning messages -respect-parentheses settings remain in effect until parenthesis boundary -sampling-factor geometry horizontal and vertical sampling factor -scene value image scene number -seed value seed a new sequence of pseudo-random numbers -size geometry width and height of image -support factor resize support: > 1.0 is blurry, < 1.0 is sharp -synchronize synchronize image to storage device -taint declare the image as modified -transparent-color color transparent color -treedepth value color tree depth -tile repeat composite operation across and down image -units type the units of image resolution -verbose print detailed information about the image -virtual-pixel method virtual pixel access method -white-point point chromaticity white point Image Operators: -blend geometry blend images -border geometry surround image with a border of color -bordercolor color border color -colors value preferred number of colors in the image -decipher filename convert cipher pixels to plain pixels -displace geometry shift lookup according to a relative displacement map -dissolve value dissolve the two images a given percent -distort geometry shift lookup according to a absolute distortion map -encipher filename convert plain pixels to cipher pixels -extract geometry extract area from image -geometry geometry location of the composite image -identify identify the format and characteristics of the image -monochrome transform image to black and white -negate replace every pixel with its complementary color -profile filename add ICM or IPTC information profile to image -quantize colorspace reduce colors in this colorspace -repage geometry size and location of an image canvas (operator) -rotate degrees apply Paeth rotation to the image -resize geometry resize the image -sharpen geometry sharpen the image -shave geometry shave pixels from the image edges -stegano offset hide watermark within an image -stereo geometry combine two image to create a stereo anaglyph -strip strip image of all profiles and comments -thumbnail geometry create a thumbnail of the image -transform affine transform image -type type image type -unsharp geometry sharpen the image -watermark geometry percent brightness and saturation of a watermark -write filename write images to this file Image Stack Operators: -swap indexes swap two images in the image sequence Miscellaneous Options: -debug events display copious debugging information -help print program options -list type print a list of supported option arguments -log format format of debugging information -version print version information By default, the image format of `file' is determined by its magic number. To specify a particular image format, precede the filename with an image format name and a colon (i.e. ps:image) or specify the image type as the filename suffix (i.e. image.ps). Specify 'file' as '-' for standard input or output.
Add Watermark
Run the following command to add the watermark. Composite command is the part of Imagemagick lib.
composite -gravity southeast -geometry +10+10 -dissolve 75% "watermark.jpg" "youtube.jpg" "youtube-with-watermark.jpg"
The watermark picture is located on the low right corner with 10px margin. A little bit transparent on the watermark.
The watermark file is a jpg file in this example. I can also use a png file, which can be a transparent file.
Add a Transparent png watermark on the image
Now I put the watermark on the left low corner.