Resize with ImageMagick with a maximal width / height

Question

The command

imageconvert.exe in.jpg -resize 800x600 out.jpg

resizes the image so that it keeps original ratio, with maximum width of 800, and

Answer 1

I think you need the > flag on the resize. Let's create some images (one red 300x200, another blue 1000x500):

convert -size 300x200 xc:red   small.png
convert -size 1000x500 xc:blue large.png

Now convert them both to 800x600 with no flags:

convert small.png -resize 800x600 a.png   # 800x533
convert large.png -resize 800x600 b.png   # 800x400

Now with flags:

convert small.png -resize 800x600\> a.png # 300x200
convert large.png -resize 800x600\> b.png # 800x400

You may need a caret (^) rather than a backslash on Windows.

The various flags are explained in the documentation here. Thanks to @user1133275 for the suggestion.