[R] Image processing in R for BMI calculation

Mon Mar 1 23:02:34 CET 2021

This discussion is completely offr topic here. Please take it elsewhere.

Bert Gunter

"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )

On Mon, Mar 1, 2021 at 1:42 PM Sorkin, John <jsorkin using som.umaryland.edu>
wrote:

> Colleagues,
>
> BMI has is failures, but it has demonstrated utility. BMI predicts
> multiple outcome measures including cardiovascular disease and mortality.
> Don't through out a useful metric because it is not the perfect metric.
>
> As to why BMI is computed as weight/height^2, it can be shown that
> dividing height by the square of weight decreases the correlation between
> weight and height. The optimum exponent (i.e. the power that most
> effectively minimizes the correlation between weight and height) is not the
> same in men and women and it differs by race. In general an exponent of 2.0
> is best for men; for women an exponent of 2.2 is a bit better than 2.0.
>
> In any event, don't let the perfect get in the way of the good.
>
> John
>
>
> John David Sorkin M.D., Ph.D.
> Professor of Medicine
> Chief, Biostatistics and Informatics
> University of Maryland School of Medicine Division of Gerontology and
> Geriatric Medicine
> Baltimore VA Medical Center
> 10 North Greene Street
> GRECC (BT/18/GR)
> Baltimore, MD 21201-1524
> (Phone) 410-605-7119
> (Fax) 410-605-7913 (Please call phone number above prior to faxing)
>
>
>
> ________________________________________
> From: R-help <r-help-bounces using r-project.org> on behalf of Jim Lemon <
> drjimlemon using gmail.com>
> Sent: Monday, March 1, 2021 4:23 PM
> To: Richard O'Keefe; r-help mailing list
> Subject: Re: [R] Image processing in R for BMI calculation
>
> I must agree with the criticism of BMI as a diagnostic index. It is
> easy to tell if a person is - ahem - wide and not very high with a
> single glance. These elementary parameters can easily be deduced from
> an image of said person. However, it does not convey that essential
> ratio of muscle to - ahem - adipose tissue that is the stated reason
> for its prominence. I suggest an older, but more valid, index that was
> used in the identification of witches. Simply tie the person's hands
> behind their back and throw him or her into the deep end of the pool.
> Time to drowning is the response variable and I am certain that those
> now chastised for their adipose tissue will vastly prefer it.
>
> Jim
>
> On Mon, Mar 1, 2021 at 10:24 PM Richard O'Keefe <raoknz using gmail.com> wrote:
> >
> > "Body Mass Index" is a rather bizarre thing:
> > body.mass.in.kg / height.in.m^2
> > I have never been able to find any biological
> > or physical meaning for this.  Yet clinicians
> > are solemnly advised to measure the weight to
> > the nearest 0.1kg and the height to the
> > nearest 0.1cm.
> >
> > How do you propose to determine the weight from
> > a single image?  Even an R package cannot perform magic.
> >
> >
> > On Mon, 1 Mar 2021 at 05:39, Paul Bernal <paulbernal07 using gmail.com> wrote:
> >
> > > Hello everyone,
> > >
> > > Does anyone know about any package for image processing, for example,
> to
> > > calculate body mass index pased on a picture, silouette or image.
> > >
> > > Any guidance will be greatly appreciated.
> > >
> > > Best regards,
> > >
> > > Paul
> > >
> > >         [[alternative HTML version deleted]]
> > >
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