Legacy ImageMagick Discussions Archive

I am trying to create an image for display on a screen, but then to print it at 300 dpi. I read this: http://www.imagemagick.org/Usage/text/#pointsize
but still have questions. Say I want the printed image to be 6 inches x 5 inches. The total "pixels" would be 1800x1500. I want to display something smaller, so I choose a proportion of 20% or 360 x 300. This example is for discussion purposes only. Say I want to add the text to be 1 inch tall (line height). What would be the best way to do this for best result and am I on the right track?
Would I create an image 1800x1500 and then add text with a pointsize of 72 to get the printable graphic and then resize it to 20% for the display graphic ignoring density or is there a better or more correct way to do this? I will also want to create a pdf of the printable graphic. Any suggestions?

Any help?

I would suggest that you set -density to 300 first, then specify a pointsize if 72. You can generate the text as a label: caption: or just draw it using -annotate. Any of then will be fine.

However be warned that the actual height of the font can vary greatly. The pointsize of a font is not its hight but the line spacing of the font. It comes from the time of printing presses where line spacing was everything. This is why many fonts seem smaller or larger than they should be, even though they are the same point size.

As you are trying to get a specific size I would start with a canvas of the size wanted, (or slightly smaller if you want finish with a border or frame) then either draw (annotate) on that canvas, or compose a second image containing the text. The first is simpler, but the second offers the possibility to use compound font techniques (shadows, distorts, outlines etc).

As another image is involved either use that image to create the canvas, or if the image will not take up all the space, or multiple images are going to be use, compose it onto a starting canvas.

Basically there are LOTS of ways to achieve your results, thing about what you want and do it. This of images more as cut out bits of paper that you can also stretch and resize, and you generally can't go wrong. Also the more techniques you know the easier it gets, and that is where IM examples can help.

Anthony, thanks for the response. I think I understand the font sizing. I have a couple of followup questions. So if I create the large image and resize or resample it down 80% for screen display is the way to go? Also, if I put the full size image with the 300 density in a pdf and print it, will it print the correct size image just as if I sent the image to the printer out of an imaging software?

TDITTBERNER wrote:Anthony, thanks for the response. I think I understand the font sizing. I have a couple of followup questions. So if I create the large image and resize or resample it down 80% for screen display is the way to go?

That will work. for that -resample 72 (or 90 depending on you display) will do the job.
Under linux you can use "xdpyinfo" to get X window screen resolution (if it was set properly).

My own workstation is reporting a 96x96 dpi resolution, though I have a feeling that is not that exact. Most people don't compare a real world object against a vertical screen. A 'light table' on the other hand is a different matter, as you can stack a physical page on top of or next to a displayed page for comparison.

It can be set or changed, though exactly how has changed with the newer Xorg server. Then again we may be using Wayland, or some other windows display driver in the near future! Linux is at a cross roads in that regards as X windows was designed for network displays of remote machines, and not for video/composition/audio/touchscreen usage that is required by modern computer displays.

Sorry I'm rambling. X windows was where I did my first graphical programming, and I recently attended a linux conference this year. -- I stop now...

Also, if I put the full size image with the 300 density in a pdf and print it, will it print the correct size image just as if I sent the image to the printer out of an imaging software?

Now that I couldn't tell you. Ideally it should. Try it an let us know!

NOTE if the PDF is saved with a 600 dpi image, or even at the display quality default of 72dpi, a 300dpi printer should scale things appropriately too. Ditto for any PDF display program, though as I said, the display resolution such a program gets may not be quite right.