How to extract images from PDF on Linux?

I have a PDF file that has some images in it. How to extract the images out (not snapshot/screenshot of the page areas) from PDF on Linux? 2 tools that I usually use for extracting and saving images from PDF files: pdfedit and libreoffice. You can open the PDF file by the tools, right click the image and you can see options like “save image” to save the image. » Read more

How to convert tiff images from RGB color to CMYK color on Linux?

I have a poster to be submitted to the publisher which requires image files in CMYK color. The file I already have is in RGB color. How to convert it on Linux? The convert tool from ImageMagick with option -colorspace to alternate image colorspace of images. The plain output with colorspace is quite large. So we’d better use a compression like LZW when writing the image: $ convert from.tif -colorspace cmyk -compress LZW to.tif To find more supported colorspace and compress options, you can use the -list option of convert: $ convert -list colorspace CIELab CMY CMYK Gray HCL HCLp HSB HSI HSL HSV HWB Lab LCH LCHab LCHuv LMS Log Luv OHTA Rec601Luma Rec601YCbCr Rec709Luma Rec709YCbCr RGB scRGB sRGB Transparent XYZ YCbCr YDbDr YCC YIQ YPbPr YUV and $ convert -list compress B44 B44A BZip DXT1 DXT3 DXT5 Fax Group4 JBIG1 JBIG2 JPEG JPEG2000 Lossless LosslessJPEG LZMA LZW None Piz Pxr24 RLE Zip RunlengthEncoded ZipS Answered by Eric Z Ma. » Read more

How to change the DPI of tiff images exported by PowerPoint?

The DPI of the tiff images exported by PowerPoint seems 96. For posters, larger DPIs like 150 or 300 are needed. Is it possible to change the DPI of tiff images exported by PowerPoint? In the options of PowerPoint, there is a setting for choosing DPIs. However, it have no effect. Check the post on changing the DPIs of PowerPoint exported slides images: How to change the DPI of images exported from PowerPoint slides Answered by Eric Z Ma. » Read more

How to convert .pptx slides to .jpg or .png images on Linux in command line?

How to convert .pptx slides to .jpg or .png images on Linux in command line? This following method works best for me. First, convert .pptx file to .pdf using libreoffice: libreoffice --headless --convert-to pdf file.pptx --headless makes libreoffice run in batch mode and not start the GUI. The pdf file will be named file.pdf by replacing the .pptx with .pdf in the original file name. » Read more

How to detect whether an image is almost blank on Linux?

How to detect whether a .jpg image is almost blank/black on Linux? Here is a bash function that I used to detect whether an image is black on Linux: function isBlank () { mean=`convert $1 -format "%[mean]" info:` echo "$mean" } It uses ImageMagic to generate formatted image characteristics (the mean). If the mean is 0, it is a black image. » Read more

Set the image size in markdown syntax

When I add an image in editor using the markdown syntax, I want to control the size of the image to display instead of its original size. How should I do this? As far as I know, the syntax of markdown currently does not support setting the size of image. If you want to set the size of the image, use the HTML stntax directly: <img src="" alt="img text" /> Answered by anonymous. » Read more