Does PurePDF support transparent PNG files?
Yes, PurePDF fully supports PNG files with transparency (alpha channel). Transparent areas are rendered against a solid white background in the PDF output, since the PDF format uses opaque white pages by default. The image content, colors, and proportions are preserved exactly as they appear. This is the standard behavior for all PDF converters — no format currently supports true transparency in embedded raster images. If you need a custom background color other than white, you would need to flatten the PNG in an image editor before uploading.
Will converting PNG to PDF reduce the image quality?
PNG is a lossless format, so the source file has no compression artifacts to begin with. PurePDF re-encodes images as JPEG internally for PDF storage, which introduces some lossy compression. At the default quality setting of 92%, the difference is virtually imperceptible to the human eye for most content. For logos, UI mockups, or pixel art where sharpness matters critically, increase the quality slider to 100% to minimize any re-encoding loss. For general sharing or archival purposes, the default 92% setting provides an excellent balance between quality and file size.
Is there a difference between converting a PNG screenshot vs a PNG photo?
The conversion process is identical — both file types are handled the same way technically. However, screenshots typically contain sharp text, hard edges, and flat colors, which are where JPEG compression is most noticeable. If your PNG is a screenshot with fine text, using a higher quality setting (95–100%) will ensure the text remains crisp in the output PDF. Photographs and gradient-heavy images compress very well at the default 92% setting. In all cases, you can preview the output before downloading to check sharpness.
Can I convert multiple PNG files into a single PDF?
Yes. You can drop as many PNG files as you like into the upload zone, and they will all be combined into a single multi-page PDF. Each PNG file becomes one page in the document. The order of pages matches the order of the thumbnails in the upload area, which you can rearrange by dragging before converting. There is no enforced limit on the number of files — however, very large batches with high-resolution images may require more time and memory.
Does this tool work with PNG files that have an alpha channel?
Yes, PNG files with full or partial alpha channel transparency are supported. The alpha information is used during rendering — pixels with partial transparency are blended against a white background before being embedded in the PDF. Fully transparent pixels become white. This means that logos with soft shadow effects, icons with feathered edges, and UI screenshots with semi-transparent overlays will all render cleanly in the output PDF. The blending is handled automatically and requires no manual configuration.
What is the difference between PNG to PDF and JPG to PDF conversion?
The main practical difference is the source format: PNG is lossless and supports transparency, while JPEG is lossy and does not support transparency. When converting to PDF, both formats go through the same rendering pipeline in PurePDF. PNG files tend to be larger on disk, especially for screenshots or graphics with large areas of flat color. JPEG files are typically smaller, especially for photographs. The PDF output quality and behavior is the same for both — the difference lies in what the original file contains, not in how PurePDF handles the conversion.
Are my PNG files safe and private?
Your PNG files never leave your device. All processing happens locally in your browser using the Canvas API — no data is transmitted to any server at any point. PurePDF has no backend infrastructure that touches your files. This means your logos, mockups, screenshots, and other sensitive graphics remain completely confidential. You can verify this by converting a file while monitoring your network traffic — you will see no upload activity.
What happens to very large PNG files — will they fail to convert?
Very large PNGs (for example, high-DPI screenshots or print-resolution graphics above 10,000 pixels wide) can use significant memory when loaded into the browser canvas. Most modern browsers handle files up to 20–30 MB without issues. If you encounter slowdowns or crashes with very large files, the best approach is to resize the image to the resolution you actually need before converting — for a standard A4 PDF viewed on screen, 2480 × 3508 pixels at 300 DPI is more than sufficient. The converter itself has no server-imposed size limit.
Can I choose different page orientations for different PNG files?
Currently, all pages in a conversion batch use the same orientation setting. PurePDF automatically determines the best fit — landscape or portrait — based on the image's own dimensions when you select "Original" page size. If you choose A4 or Letter, the image is scaled proportionally to fit within the page margins regardless of orientation. If you need a mix of orientations in a single PDF, the most reliable approach is to convert portrait and landscape images separately and then use the PDF Merger tool to combine them in your desired order.
Does PurePDF preserve the original PNG resolution in the output PDF?
When you choose "Original" page size, the PDF page dimensions are set to match the image's natural dimensions in points. A 1200 × 900 pixel image, for example, produces a PDF page sized accordingly, embedding the image at its full native resolution. When you choose A4 or Letter, the image is scaled to fit the page while maintaining its aspect ratio, but the underlying pixel data is not degraded beyond the JPEG quality setting. For print-quality output, always use the "Original" page size and a high quality setting to preserve maximum detail.