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revise vipsthumbnail tutorial 

Some of the args have changed slightly.
This commit is contained in:
John Cupitt 2020-01-14 17:10:31 +00:00
parent 285f6c7418
commit 70e8c6a61f
3 changed files with 36 additions and 46 deletions
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18
doc/How-it-opens-files.md
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@ -1,13 +1,13 @@
<refmeta>
<refentrytitle>Opening files</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>libvips</refmiscinfo>
</refmeta>
<refmeta>
<refentrytitle>Opening files</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>libvips</refmiscinfo>
</refmeta>
<refnamediv>
<refname>Opening</refname>
<refpurpose>How libvips opens files</refpurpose>
</refnamediv>
<refnamediv>
<refname>Opening</refname>
<refpurpose>How libvips opens files</refpurpose>
</refnamediv>
libvips now has at least four different ways of opening image files, each
best for different file types, file sizes and image use cases. libvips tries

46
doc/Using-vipsthumbnail.md
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@ -1,13 +1,13 @@
<refmeta>
<refentrytitle>Using `vipsthumbnail`</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>libvips</refmiscinfo>
</refmeta>
<refmeta>
<refentrytitle>Using `vipsthumbnail`</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>libvips</refmiscinfo>
</refmeta>
<refnamediv>
<refname>`vipsthumbnail`</refname>
<refpurpose>Introduction to `vipsthumbnail`, with examples</refpurpose>
</refnamediv>
<refnamediv>
<refname>`vipsthumbnail`</refname>
<refpurpose>Introduction to `vipsthumbnail`, with examples</refpurpose>
</refnamediv>
libvips ships with a handy command-line image thumbnailer, `vipsthumbnail`.
This page introduces it, with some examples.
@ -270,12 +270,15 @@ $ ls -l tn_shark.jpg
Now encode with sRGB and delete any embedded profile:
```
$ vipsthumbnail shark.jpg --eprofile /usr/share/color/icc/sRGB.icc --delete
$ vipsthumbnail shark.jpg --eprofile srgb --delete
$ ls -l tn_shark.jpg
-rw-r–r– 1 john john 4229 Nov  9 14:33 tn_shark.jpg
```
It’ll look identical to a user, but be almost half the size.
(You can use the filename of any RGB profile. The magic string `srgb` selects a
high-quality sRGB profile that's built into libvips.)
`tn_shark.jpg` will look identical to a user, but it's almost half the size.
You can also specify a fallback input profile to use if the image has no
embedded one. This can often happen with CMYK images, producing an error
@ -291,23 +294,11 @@ If you supply a CMYK profile, it will be able to convert the image,
for example:
```
$ vipsthumbnail kgdev.jpg --iprofile /usr/share/color/icc/colord/FOGRA28L_webcoated.icc
$ vipsthumbnail kgdev.jpg --iprofile cmyk
```
I've had good results with this profile:
https://github.com/libvips/nip2/blob/master/share/nip2/data/cmyk.icm
It makes nice-looking images from most CMYK files, and is completely free.
# Auto-rotate
Many JPEG files have a hint set in the header giving the image orientation. If
you strip out the metadata, this hint will be lost, and the image will appear
to be rotated.
If you use the `--rotate` option, `vipsthumbnail` examines the image header and
if there's an orientation tag, applies and removes it.
(As before, the magic string `cmyk` selects a high-quality CMYK profile that's
built into libvips, but you can use any CMYK profile you like.)
# Final suggestion
@ -317,6 +308,5 @@ Putting all this together, I suggest this as a sensible set of options:
$ vipsthumbnail fred.jpg \
--size 128 \
-o tn_%s.jpg[optimize_coding,strip] \
--eprofile /usr/share/color/icc/sRGB.icc \
--rotate
--eprofile srgb
```

18
doc/binding.md
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@ -1,13 +1,13 @@
<refmeta>
<refentrytitle>How to write bindings</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>libvips</refmiscinfo>
</refmeta>
<refmeta>
<refentrytitle>How to write bindings</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>libvips</refmiscinfo>
</refmeta>
<refnamediv>
<refname>Binding</refname>
<refpurpose>Writing bindings for libvips</refpurpose>
</refnamediv>
<refnamediv>
<refname>Binding</refname>
<refpurpose>Writing bindings for libvips</refpurpose>
</refnamediv>
There are full libvips bindings for quite a few environments now: C, C++,
command-line, Ruby, PHP, Lua, Python and JavaScript (node).