Pdf to image

Web applications dealing with pdfs sometimes need to create a image or
thumbnail of the uploaded pdf. Over here we are going to use
imagemagick to convert pdfs to images.

The simplest command to do the task is ...

$ convert demo.pdf demo.jpg

The above command shall generate the jpg format image from the pdf
file. If the pdf file has multiple pages then imagemagick shall create
multiple image files named as demo-1.jpg, demo-2.jpg ... for as many
pages as there are in the pdf file.

To convert only a particular page from the pdf file use the following
command

$ convert demo.pdf[2] demo.jpg

The 2 in the bracket indicates the index of the page. 0 means the
first page and then increment 1 for each page.

Creating thumbnails

To create thumbnail, the image just needs to be scaled down using
either of the 'scale', 'thumbnail' or 'resize' option. Here is a quick
example.

$ convert -thumbnail x300 demo.pdf[2] demo.jpg

The above will create a thumbnail image of height 300px and correct
width according to aspect ratio of the original pdf.

If the pdf has transparency then scaling might result into an image
where all white areas turn into black. To fix this the 'flatten'
option can be used as follows

$ convert -thumbnail x300 demo.pdf[2] -flatten demo.jpg

The above command shall put a white background in the transparent
areas.

Clearer text

Using the above command you might notice that the text in the
resulting image is not clear or sharp. This can be fixed using the
'density' option. Use a value of around 175 and the text should become
clearer than before. Experiment with the value till the desired level
of sharpness is achieved.

$ convert -density 200 -scale x800 demo.pdf[2] demo.jpg

Create gif animation of all pages

Imagemagick can even create a gif animation of all the pages of the
pdf. Its as simple as the following command







$ convert -thumbnail x300 -delay 100 demo.pdf demo.gif

The delay parameter defines the delay of animation.

Quality/compression for jpg

The quality or compression level of jpg images can be specified using
the 'quality' option

$ convert demo.pdf[0] -scale x800 -quality 75 -flatten demo75.jpg

Higher quality image would have lesser compression and larger file
size as a result.  Last Updated On : 14th November 2012



Use:

convert demo.pdf[0] -scale x800 -quality 75 -flatten demo75.jpg

for i in *.pdf; do convert -thumbnail x500 ${i}[0] -flatten ${i/.pdf}.jpg; done;

for i in *.pdf; do convert -thumbnail x500 ${i}[0] -flatten ${i/.pdf/.jpg}; done;


Other useful shell commands:

for i in *.JPG; do mv $i ${i/.JPG}.jpg; done