Understanding PDF Compression
Whether you're applying for a job or sending a contract, being limited by email attachment sizes is a common frustration. But simply "shrinking" a PDF can often result in unreadable text or pixelated images. Here is how to do it right.
Lossy vs. Lossless Compression
PDFs contain various elements: text (usually vector), images (raster), and structural metadata. Text and vectors can typically be compressed losslessly, meaning no data is lost. Images, however, are usually compressed using "lossy" methods like JPEG where some quality is sacrificed for space.
Optimizing Images
The biggest factor in PDF size is usually high-resolution images. For most business documents, a resolution of 150 DPI is more than enough for clear printing, while 72 DPI is perfect for screen viewing. Reducing a 300 DPI image to 150 DPI can often cut your file size by 75% without any noticeable change in quality.
Removing Redundant Data
Many PDFs contain embedded fonts or hidden metadata that isn't necessary for viewing. Professional tools like PDFBridge automatically identify and remove this redundant information to give you the smallest possible file size while keeping your document looking professional.