Simple GIMP question

[TonyAimer]

I am using GIMP 2.10.18

I wanted to create a geometric object in GIMP but decided to do it in AutoCAD and plotted it as a pdf which worked fine. I did it white on black in Acad and it came out fine as black on white as a pdf.

I tried to import it to GIMP and rotate and resize it to suit the Youtube icon of 300x300 pixels.

I got what appears to be a transparency layer added but there is only one layer containing the pdf.  I am obviously missing something but if this workflow is fundamentally incorrect it would be good to know. 

Any tips would be welcome.

Tony

[rich2005]

Us poor people have to use LibreCAD

Your PDF from CAD might look like this, a drawing on a page. This one A4 paper size.

   

Gimp is a raster editor, any vector properties of the CAD design are lost. Quality all depends on the image resolution. If the import dialogue resolution is not 300 pixels-per-inch then bump it up, 300 ppi is the usual quality value. Then edit as required, crop and scale to 300 x 300 pix 

   

If it is a logo, or part of a logo, you might want to consider the vector program Inkscape. That will keep the vector properties of the PDF. Saving as a scaleable-vector-graphics ( SVG ) format makes the image easily scalable up or down, or if you want a 300 x 300 pix png you can export that.

   

[TonyAimer]

Thanks for your response.

I need to establish what resolution ACAD 2011 produces when it plots a pdf.

I am hoping that a pdf is therefore is then in raster format and will be OK in GIMP.

Tony

[denzjos]

@TonyAimer, using LibreCAD, one can export a file as an SVG file. One can load this file in Gimp and the result is a path. One can scale and make some corrections on the result with paths in Gimp. Then one can use all the things that Gimp offer to color the path.
   

[rich2005]

(01-07-2024, 06:04 AM)TonyAimer Wrote: Thanks for your response.

I need to establish what resolution ACAD 2011 produces when it plots a pdf.

I am hoping that a pdf is therefore is then in raster format and will be OK in GIMP.

Tony

Really a PDF is a 'final' format. It is not meant for format exchange. As the acronym Portable Document, when composed of text and vectors it does not have a defined resolution, it will display small or large. Raster (bitmap) images do have a resolution, a scanned document for example where the scan resolution might be 100 ppi (low quality) or 300 ppi (high quality) and you will see difference in quality when you zoom in on a PDF. Just the same as scaling a small image in Gimp.

The PDF from CAD is a vector so does not have a defined resolution. It is up to you to make that definition when you import into Gimp. It used to default to 100 ppi leaving the user to increase as required, it seems Gimp 2.10.36 now defaults to 300 ppi which makes it less of a stumbling block for new users.

ACAD will be using real world units inches or millimetres. A simple calculation if you know the size of the logo.
Say you have drawn it 2 inches x 2 inches. You want it as a 300 x 300 pix image for YT 300 / 2 = 150 ppi
Import the PDF into Gimp and set the resolution in the import dialogue to 150

[TonyAimer]

I thought a pdf file was a raster image but I seem to be wrong.

That's how I send printable copies of my drawings in dwg format to clients by sending them files plotted in pdf format.

No complaints in that regard and I sometimes see printed copies of my drawings on sites.

In desperation I have made a freehand logo/icon for my youtube channel in the meantime.

I have librecad on this Linux machine so I will try drawing and exporting from that as recommended.

Thanks for the replies

Tony