What is a PNG file?

PNG is a type of file format that is very popular to use today. The full name of PNG is Portable Network Graphics, it is is a raster-graphics file format that supports lossless data compression. PNG supports full-color non-palette-based RGB or RGBA pictures as well as palette-based images (palettes with 24-bit RGB or 32-bit RGBA colors), alpha-channel with or without transparency, and grayscale images. Non-RGB color spaces like CMYK are not supported since the PNG working group created the format for Internet image transfer rather than for high-quality printed graphics.

Characteristics of PNG format

Transparency of image

• You can easily specify a transparent background for PNG format. PNG provides numerous choices for transparency. Individual pixel values for true color and grayscale images can be set to be transparent, or an alpha channel can be added (allowing any percentage of partial transparency). The alpha value can be added to the palette entry for images that have been paletted.

Animation

• Animation is not natively supported by PNG. MNG was created by PNG group members and is an extension of PNG. MNG has a similar basic structure to PNG and uses many of the same building elements, but it is far more complicated and has a separate file signature, making it incompatible with PNG decoders that are used by most online browsers or applications.

Pixel format

• The numbers that make up pixels in PNG images can either be indices into the sample data in the palette or the sample data itself. The PLTE block contains a distinct table called the palette. A single pixel’s sample data is made up of tuples of one to four numbers. Every integer in the image is encoded using the same structure, regardless of whether the pixel data represents a palette index or an explicit sample value.

Advantages of PNG

Efficiency

• In terms of efficiency, PNG is efficient in decoding and rendering for any progressive image rendering, compression and filtering

Flexibility

• In terms of flexibility, future additions and private extensions are permitted without altering the preceding sentence.

Completeness

• It can represent true color, indexed-color, and greyscale images.

Compression

• You can compress the PNG efficiently and consistently.

Freedom of legal restrictions

• The algorithms used are free and accessible for people.

Compare with other file formats

Graphics Interchange Format (GIF)

• For most of the images,  a GIF file has a larger size than an indexed PNG image.
• PNG gives a much wider range of transparency options than GIF
• When converting an image from the PNG format to GIF, the image quality may be affected

JPEG

• PNG format can compress image data more than JPEG
• JPEG does not support transparency

TIFF

• PNG supports non-premultiplied alpha only while TIFF also supports premultiplied alpha.

JPEG-LS

• JPEG-LS generally performs better than PNG
• Both PNG and JPEG-LS formats are options and file size is an important criterion

Convert PNGs to PDFs

On how to change PNG into PDF. It’s simple. You can just access Adobe Acrobat online services using any web browser, then find the convert JPG to PDF page. To upload an image file, drag it into the drop zone or choose the “Select A File” button.

Edit the PDF documents with Visual Paradigm Online Free PDF Editor

Visual Paradigm now provides a new feature for editing PDFs. You can easily upload any PDF files and modify the PDF. It is easy to use for everyone to customize the original PDF on your own like editing the content, adding images, table/charts, or other design features. You can click on here to check out VP Online Free PDF editor.

In VP Online, you can use the upload PDF tab above to submit your PDF file. You can select a file from your online drives, including Google Drive, Dropbox, or drag and drop a file.

The document’s text and pictures can both be changed. Double-click the text shape to adjust the settings for the content and font. Select a shape or picture to edit it, then make adjustments like resizing, adding effects, and more.

After finished your editing, you can share the revised PDF online or download it. It is easy for everyone to edit PDFs with Visual Paradigm Online PDF Editor.