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inkscape
Find the unicode number corresponding to the greek character you want to
include. Tables of codes can be found in Unicode Charts
. For
example, the unicode for the alpha symbol is 03b1.
In a text cell type Ctrl-u, include the unicode key of the greek letter and press enter.
Gimp
Find the unicode number corresponding to the Greek character you want to
include. Tables of codes can be found in Unicode Charts
. For
example, the unicode for the alpha symbol is 03b1.
In a text cell type Ctrl-Shft-u, include the unicode key of the Greek letter and press enter.
inkscape
In order to include sub and super-indexes in inkscape
you can
change the text base line in a text cell using the keys:
Alt-Up and Alt-Down.
ImageMagick
to transform graphic filesUpdated on July 06th, 2014; September 22nd, 2016.
You can easily transform a graphic file from the console using the tool
convert from the ImageMagick
suite. Imagine for
example that we start with the file foto_0.png.
$ identify foto_0.png foto_0.png PNG 1209x1710 1209x1710+0+0 DirectClass 8-bit 2.63038mb
We have made use of the command identify, that is also part of the
ImageMagick
suite and describes the format and characteristics of
image files. There are several ways to resize the file. The common syntax is
convert -resize geometry. From the many possible ways
of expressing the geometry change we present three useful options:
scale%: Height and width scaled by the specified percentage scale.
width: Width fixed to width and height automatically rescaled to conserve aspect ratio.
xheight: Height fixed to height and width automatically rescaled to conserve aspect ratio.
We present examples of the three possibilities[15]:
$ identify foto_0.png foto_0.png PNG 1209x1710 1209x1710+0+0 DirectClass 8-bit 2.63038mb $ convert -depth 8 -resize 50% foto_0.png foto_1.png $ identify foto_1.png foto_1.png PNG 605x855 605x855+0+0 DirectClass 8-bit 681.391kb $ convert -depth 8 -resize 1024 foto_0.png foto_2.png $ identify foto_2.png foto_2.png PNG 1024x1448 1024x1448+0+0 DirectClass 8-bit 1.82886mb $ convert -depth 8 -resize x800 foto_0.png foto_3.png $ identify foto_3.png foto_3.png PNG 566x800 566x800+0+0 DirectClass 8-bit 601.271kb
Apart from resizing images we can also transform from an image format to a different one. For example, to convert from encapsulated postscript (eps) to png format:
$ identify bsplot_N40.eps bsplot_N40.eps PS 613x661 613x661+0+0 16-bit DirectClass 20.4KB 0.000u 0:00.000 $ convert bsplot_N40.eps bsplot.png $ identify bsplot.png bsplot.png PNG 613x661 613x661+0+0 8-bit PseudoClass 6c 8.64KB 0.000u 0:00.000
Convert can be also used to stack horizontally or vertically several images. For example, the command
$ convert Glacial_Map_0.jpg Glacial_Map_1.jpg Glacial_Map_2.jpg +append test.png
will produce a file test.png
that includes the three figures
appended in a row. To append them vertically the option is
-append.
Gimp
A Gimp
filter that improves and sharpen lines when colors are too
weak can be found in
Filters -> Enhance -> Unsharp Mask
Gimp
In order to remove the background of an image using Gimp
a
possible (easy) recipe is the following-,
Using the lasso tool (also known as Free Select Tool) make a rough selection around the image that you want to remove the background from.
Activate the quick mask tool by selecting the little square at the bottom left side of the main image window. Using this tool the selection can be refined.
Using the pencil tool shade the background more precisely around your image. If you make a mistake you can either use Ctrl Z to undo your last action or change the pencil to white which will remove the mask.
Toggle the quick mask off, copy the image, and paste as new. This will result in a background-free copy of your image.
To refine the final result, add alpha to the selection (from the layers tool). Then, from the Select menu: (a) invert the selection, (b) feather the selection by 1 or 2 pixels, (c) Ctrl + k to clear, and (d) Ctrl + Shift + A to unselect.
Save your image.
Gimp
In order to take a screenshot of the full display, a window, or part of a
window launch Gimp
and select
File -> Create -> ScreenShot...
It is convenient to fix a time delay to be able to select the right window to grab the region of interest.
inkscape
Added on July 06th, 2014.
In order to change the color of markers (e.g. arrows end and start) in
inkscape
to coincide with the color of the stroke of the object
they belong to the following effect should be enabled.
Extensions > Modify Path > Color Markers to Match Stroke
If
Gimp
fileAdded on November 10th, 2018
The canvas is the visible area of the Gimp
image. By
default the canvas and layers size coincides. The Canvas Size
command lets you enlarge or reduce the canvas size. You can also modify the
size of the layers. You can access this command from the image menubar through
Image -- Canvas Size.
When you enlarge the canvas, you create free space around the contents of the image. When you reduce it, the visible area is cropped, however the layers still extend beyond the canvas border.
When you reduce the canvas size, the new canvas appears surrounded with a thin negative border in the preview. The mouse pointer is a moving cross: click and drag to move the image against this frame.
Added on October 24th, 2017.
If you need to extract images from a pdf file a convenient
terminal application is pdfimages
. For example if we need to
extract the images from a file named article.pdf
you can proceed
as follows
$ pdfimages -all article.pdf ./article_images $ ls article.pdf article_images-003.tif article_images-006.tif article_images-000.tif article_images-004.pbm article_images-007.tif article_images-001.tif article_images-004.png article_images-002.tif article_images-005.tif
The article contains seven images. The options -all indicate that JPEG, JPEG2000, JBIG2, and CCITT images are extracted in their native format while CMYK files are written as TIFF files and all other images are written as PNG files.
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Some Mini-Howtos of Interest
Curro Perez-Bernalmailto:francisco.perez@dfaie.uhu.es