Add minScale to image config

[nibe]

$image.Fill with the default smart cropping unnecessarily crops images. Example:

{{ with .Resources.GetMatch "example.jpg" }}<!-- 300x200 px -->
  {{ $smart := .Fill "150x100" }}<!-- Same aspect ratio, no need to crop! -->
  {{ $expected := .Fill "150x100 Center" }}
  <img src="{{ .RelPermalink }}">
  <img src="{{ $smart.RelPermalink }}">
  <img src="{{ $expected.RelPermalink }}">
{{ end }}

example.jpg:

Smart crop (feathers chopped off, unnecessary because same aspect ratio):

Expected:

This does not just apply when the aspect ratio is the same, it unnecessarily crops whenever it feels like it. I would rather not use another anchor because smart cropping would be super useful if it only cropped when necessary. I filed this as a bug rather than a feature request because it is the default behavior and unexpected (for me).

smartcrop.js (which the smartcrop library used in Hugo is based on) has the following option, which appears to prevent this issue: minScale: minimal scale of the crop rect, set to 1.0 to prevent smaller than necessary crops (lowers the risk of chopping things off).

What version of Hugo are you using (hugo version)?

$ hugo version
hugo v0.114.0+extended darwin/amd64 BuildDate=unknown

Does this issue reproduce with the latest release?

Yes.

[jmooring]

Somewhat related: muesli/smartcrop#21

Without being configurable, this would change images in the wild. So, proposal instead of bug.

[nibe]

I just tested it and minScale in smartcrop.go does indeed cause this issue. It's set to 0.9 and changing it to 1.0 stops unnecessary cropping. Unfortunately, it is a constant.

[nibe]

I found a workaround by the way. First you smart crop with the aspect ratio you want, without reducing the width or height (so that minScale does not come into play). Then you downscale. This works because maxScale is 1.0.

{{ with .Resources.GetMatch "example.jpg" }}<!-- 300x200 px -->
  {{ $smart := .Fill "200x150" }}
  {{ $workaround := (.Fill "300x225 q100").Resize "200x" }}
  <img src="{{ .RelPermalink }}">
  <img src="{{ $smart.RelPermalink }}">
  <img src="{{ $workaround.RelPermalink }}">
{{ end }}

Smart (unnecessarily crops vertically):

Workaround: