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note improvements to iprofile

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The docs had fallen behind a bit ... iprofile is no longer usually necessary.

see https://github.com/libvips/libvips/issues/1843
This commit is contained in:
John Cupitt 2020-10-02 11:20:35 +01:00
parent c27c471e28
commit f2956ac069
1 changed files with 13 additions and 17 deletions
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doc/Using-vipsthumbnail.md
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@ -23,6 +23,14 @@ $image = Vips\Image::thumbnail($filename, 200, ["height" => 200]);
$image->writeToFile("my-thumbnail.jpg"); $image->writeToFile("my-thumbnail.jpg");
``` ```
You can also call `thumbnail_source` from the CLI, for example:
```
$ cat k2.jpg | \
vips thumbnail_source [descriptor=0] .jpg[Q=90] 128 | \
cat > x.jpg
```
# libvips options # libvips options
`vipsthumbnail` supports the usual range of vips command-line options. A `vipsthumbnail` supports the usual range of vips command-line options. A
@ -282,25 +290,14 @@ 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. `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 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 embedded one. For example, perhaps you somehow know that a JPG is in Adobe98
message like: space, even though it has no embedded profile.
``` ```
$ vipsthumbnail kgdev.jpg $ vipsthumbnail kgdev.jpg --iprofile /my/profiles/a98.icm
vipsthumbnail: unable to thumbnail kgdev.jpg
vips_colourspace: no known route from 'cmyk' to 'srgb'
``` ```
If you supply a CMYK profile, it will be able to convert the image,
for example:
```
$ vipsthumbnail kgdev.jpg --iprofile cmyk
```
(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 # Final suggestion
Putting all this together, I suggest this as a sensible set of options: Putting all this together, I suggest this as a sensible set of options:
@ -309,6 +306,5 @@ Putting all this together, I suggest this as a sensible set of options:
$ vipsthumbnail fred.jpg \ $ vipsthumbnail fred.jpg \
--size 128 \ --size 128 \
--eprofile srgb \ --eprofile srgb \
-o tn_%s.jpg[optimize_coding,strip] \ -o tn_%s.jpg[optimize_coding,strip]
--eprofile srgb
``` ```