how batch resize to a constant print format, aka A4 portrait

[mustbeit]

XnConvert 1.75

Thanks for XnConvert.
I don't know if this is a feature request or an already available options.
I have lot of jpegs having different pixel size for instance 768x1024, 3840x2160, 4000x3000, etc. and there dpi can be 72x72, 200x200, etc.

What I want is a batch lossless dpi change so as:
1/ that according to the pixel size of each image its dpi is always MAX to the an A4 print size in a given orientation(and preserves aspect ratio).
For instance, for an image of 4000x3000 (landscape),
A4 size being 210x297mm(portrait) = 8.3 x 11.7 inches
=>4000pix must fit within 210mm/8.3inches
=> dpi = 4000/8.3 = 481.9277 = rounded to 482 - aka always rounding UP to nearest (even?) integer.

2/ set a minimum dpi, in case of low quality picture
For instance, for an image of 768x1024
If one would have in A4 portrait
768pix in 8.3inch
=> dpi = 92.53
But one could decide to set that minimum to say 120dpi, so that in this case the image is set to 120dpi and not 93 or 94 dpi.

Same ought to apply to single page PDF, if not multiple pages DPF

Thanks

REF: viewtopic.php?f=79&t=33040&p=131538&hilit=dpi#p131538

[xnview]

sorry but currently it's not possible