內容簡介
Rapls PDF Image Creator 外掛能自動生成 PDF 文件的縮圖，並將第一頁轉換為影像，提升 WordPress 媒體庫的使用體驗。透過 ImageMagick 技術，確保生成的縮圖品質優良，避免白色縮圖的問題。
【主要功能】
• 自動生成 PDF 縮圖
• 使用 ImageMagick 轉換影像
• 避免白色縮圖問題
• 提供狀態檢查與錯誤提示
• 支援 CMYK 色彩管理
外掛標籤
開發者團隊
② 後台搜尋「Rapls PDF Image Creator – PDF Thumbnails & Featured Images」→ 直接安裝（推薦）
📦 歷史版本下載
原文外掛簡介
Rapls PDF Image Creator automatically generates thumbnail images when you upload PDF files to your WordPress Media Library. The plugin uses ImageMagick (Imagick PHP extension) to convert the first page of a PDF into an image.
👉 Setup guide & troubleshooting: How to fix CMYK black thumbnails and PDF/X issues
Why this one
On a server with an older Ghostscript, a PDF page can come back completely white — and Ghostscript does not report it as an error. Anything that hands the page over and stores whatever comes back saves that white image, including WordPress’s own PDF preview. It looks like a thumbnail. It looks like the job worked.
Measured on a live shared host running Ghostscript 9.27, in a single upload: the built-in preview came back with a standard deviation of 0, one flat colour across every pixel. This plugin’s thumbnail of the same page, in the same request, came back at 0.31.
It looks at what came back. A page that renders as flat white is refused, not stored. WordPress shows its PDF icon and the Status tab says why, which is more use than a white square
It works around the cause. Ghostscript 9.27 and earlier fail on an image inside a transparency group — the kind of file PowerPoint and Illustrator produce. Retried with transparency switched off, the same page went from 11,018 bytes of white to 624,109 bytes of picture. Only ever as a retry: a page that rendered the first time is never touched
Every check is a measurement. Whether this server can read a PDF, render CMYK, or select a page other than the first is answered by doing it, not by reading a version number. The Status tab names the Ghostscript device your ImageMagick uses
It tells you what to ask your host. “No PDF support”, “the page is too large”, “the uploads folder is not writable” and “the file is missing” are four problems with four different answers, and they no longer look the same
Real colour management, without the weight. CMYK is converted through ICC profiles rather than the arithmetic shortcut that turns greens fluorescent. The bundled sRGB profile is 3 KB, not the 64 KB kind that ends up embedded in every registered size
Nothing starts a process. No exec(), no shell. It works on locked-down shared hosting
Key Features
Automatic Generation – Thumbnails are created instantly when PDFs are uploaded
Featured Image Support – Generated thumbnails are automatically set as the PDF’s featured image
Multiple Sizes – Images are generated in all registered WordPress image sizes
Media Library Integration – Display thumbnails instead of default PDF icons
Editor Integration – Insert PDF links with thumbnail images into your posts
Bulk Generation – Generate thumbnails for all existing PDFs at once
Flexible Output – Choose from JPEG, PNG, or WebP formats
How It Works
Upload a PDF file to the Media Library
The plugin automatically converts the first page to an image
The image is registered as the PDF’s featured image
Use shortcodes or template functions to display the thumbnail
Generated Files
When you upload my-document.pdf, the plugin creates:
my-document-pdf.jpg (Full size cover image)
my-document-pdf-1024×768.jpg (Large)
my-document-pdf-300×225.jpg (Medium)
my-document-pdf-150×150.jpg (Thumbnail)
Additional sizes based on your theme settings
Shortcodes
[rapls_pdf_thumbnail id="123"] – Display thumbnail image
[rapls_pdf_thumbnail_url id="123"] – Output thumbnail URL
[rapls_pdf_clickable_thumbnail id="123"] – Thumbnail linked to PDF
[rapls_pdf_download_link id="123"] – Download link with thumbnail
Template Functions
rapls_pic_get_thumbnail_url( $pdf_id, $size ) – Get thumbnail URL
rapls_pic_get_thumbnail_id( $pdf_id ) – Get thumbnail attachment ID
rapls_pic_get_thumbnail_image( $pdf_id, $size, $attr ) – Get thumbnail HTML
rapls_pic_has_thumbnail( $pdf_id ) – Check if PDF has thumbnail
rapls_pic_generate_thumbnail( $pdf_id, $force ) – Generate thumbnail
Requirements
WordPress 5.0 or higher
PHP 7.4 or higher
ImageMagick with Imagick PHP extension and PDF support
Most shared hosting providers have ImageMagick available. Check the Status tab in plugin settings to verify your server meets the requirements.
Will it work on my server?
PDF thumbnails depend on ImageMagick being able to read PDFs, and not every host allows that. Rapls PDF Image Creator checks by actually rendering a small test PDF, not by reading a configuration value, and tells you on the Status tab whether PDF rendering works on your server and, if not, what to ask your host for. Site Health flags it too when it doesn’t.
Using Template Functions
Display a PDF thumbnail in your theme:
$pdf_id = 123;
if ( rapls_pic_has_thumbnail( $pdf_id ) ) {
echo rapls_pic_get_thumbnail_image( $pdf_id, 'medium' );
}
Link thumbnail to PDF file:
$pdf_id = 123;
if ( $thumbnail_id = get_post_thumbnail_id( $pdf_id ) ) {
echo '';
echo wp_get_attachment_image( $thumbnail_id, 'medium' );
echo '';
}
Display All PDFs Attached to a Post
$pdfs = get_posts( array(
'post_type' => 'attachment',
'post_mime_type' => 'application/pdf',
'post_parent' => get_the_ID(),
'posts_per_page' => -1,
) );
foreach ( $pdfs as $pdf ) {
if ( rapls_pic_has_thumbnail( $pdf->ID ) ) {
printf(
'%s',
esc_url( wp_get_attachment_url( $pdf->ID ) ),
rapls_pic_get_thumbnail_image( $pdf->ID, 'thumbnail' )
);
}
}
Available Filter Hooks
rapls_pdf_image_creator_thumbnail_page – PDF page to use (default: 0)
rapls_pdf_image_creator_thumbnail_max_width – Maximum width
rapls_pdf_image_creator_thumbnail_max_height – Maximum height
rapls_pdf_image_creator_thumbnail_resolution – Rendering resolution in DPI (default: 150)
rapls_pdf_image_creator_thumbnail_quality – Image quality (1-100)
rapls_pdf_image_creator_thumbnail_format – Output format
rapls_pdf_image_creator_thumbnail_bgcolor – Background color
rapls_pdf_image_creator_thumbnail_image_attributes – Image tag attributes
rapls_pdf_image_creator_custom_insert_html – Custom insert HTML
rapls_pdf_image_creator_hide_thumbnails_in_library – Hide in Media Library
rapls_pdf_image_creator_policy_paths – ImageMagick policy.xml paths to search when diagnosing blocked PDF support
Color Conversion Filters
rapls_pdf_image_creator_color_conversion – auto (default), icc or naive. naive restores the pre-1.1.0 colors
rapls_pdf_image_creator_icc_paths – Array of absolute paths to search, per profile type (srgb / cmyk)
rapls_pdf_image_creator_rendering_intent – An Imagick::RENDERINGINTENT_* value (default: relative colorimetric)
rapls_pdf_image_creator_flatten_background – Background transparency is flattened onto (default: the configured background, or white for JPEG)
Pointing the plugin at a specific pair of profiles:
add_filter( 'rapls_pdf_image_creator_icc_paths', function( $paths, $type ) {
if ( 'cmyk' === $type ) {
return array( '/srv/icc/JapanColor2011Coated.icc' );
}
return $paths;
}, 10, 2 );
Available Action Hooks
rapls_pdf_image_creator_before_generate – Before thumbnail generation
rapls_pdf_image_creator_after_generate – After successful generation
rapls_pdf_image_creator_generation_failed – When generation fails
Bundled third-party assets
sRGB2014.icc
An ICC colour profile from the International Color Consortium’s profile
registry (https://www.color.org/srgbprofiles.xalter), used as the destination
profile when converting CMYK PDF pages to sRGB, and attached to the generated
image.
Licence, from https://registry.color.org/profile-library/ :
“This profile is made available by the International Color Consortium, and may
be copied, distributed, embedded, made, used, and sold without restriction.
Altered versions of this profile shall have the original identification and
copyright information removed and shall not be misrepresented as the original
profile.”
Shipped unaltered. Compatible with GPL-2.0-or-later.
No other profile is bundled. CMYK profiles are read from the host when one is
present and are never redistributed.
