What is the DPI resolution value of PDF document? - ByteScout
  • Home
  • /
  • Blog
  • /
  • What is the DPI resolution value of PDF document?

What is the DPI resolution value of PDF document?

Starting Out with React Native

We all use PDF files for one activity or the other. These documents have a significant level of functionality across different fields. In fact, most individuals and businesses prefer using PDF files as they are easier to use and more professional.

However, only a few know the internal workings of the PDF file. In particular, many don’t understand the DPI of the PDF file. PDF is a vector-based format entity and there are no “classic” dots (pixels) as one may find in JPG, PNG, TIFF pictures. In opposite, PDF format internally uses something similar to computer programs that can draw lines, circles, text, forms, etc. So PDF file is automatically executed to create a picture for various DPI (Dots Per Inch) targeting screen or printing device depending on specific monitors or printing devices accordingly.

Diving a little deeper, within a typical PDF file, what you have within is a scaling command and raw imagery, which fits within a slot on each page. The larger the imagery, then it means the slot is smaller. Therefore, you can easily zoom pages while printing high-resolution documents. As discussed earlier, the larger the file, the bigger the image. Also, you have to find the balance between the slots and the raw imagery size. Doing this allows you to get the right PDF file with a suitable resolution.

All too often, DPI and PPI are used interchangeably even though the means are different. Specifically, DPI (Dots Per Inch), is that measurement more refers to the resolution of a computer printer. While PPI (Pixels Per Inch) or pixel density is synonymous with samples per inch.

In general, DPI is considered a measure of the number of dots, which can be aligned on a line under a one-inch span. This measure could be described in terms of an image or a video scanner dot concentration and spatial printing. With particular reference to PDF, it refers to the measurement of the resolution of a computer display, correlated to the size of the display in inches and the total number of pixels in the horizontal and vertical directions. For instance, a 300 dpi PDF is a document that contains raster information sized to 300 PPI at the defined output dimensions.

Why is it important to know the DPI resolution of a document?

PDF files do not have a single DPI value, all bitmap page objects have separate resolutions, therefore, course vector objects such as text have no resolution at all. However, this flexibility allows PDF documents to be printed and displayed with the highest quality even for super large sizes. If you compare this to JPG, PNG pictures then pictures are just a set of pixels and you will see blurring effects when pictures are zoomed in or increased in size.

PDF files were designed to look crisp and clean but not bit-mapped or pixellated. Despite this, better quality PDF files are usually larger. Many designs and photo apps suggest that files should be saved as PDFs. This is a clear distinction from images, which are bit-mapped. Therefore, small images get stretched while the pixel becomes significantly more prominent. Though having clunky PDFs are great for printing but it might useful for other purposes. For instance, you might need to transfer files or upload them into a cloud network. One way to solve this is to convert PDFs into another format while maintaining a high DPI.

Additionally, the better the quality of the PDF file generated, the larger the file. As such, most PDF file generation applications give users the opportunity to create files either for printing or on-screen use. It will also benefit you to make larger files for printing if space is not an issue for you.

How to convert documents to have a better DPI for high-quality?

So if you need to convert PDF into a JPG, PNG, or TIFF picture then you should use PDF Renderer SDK and just set the size and resolution of the output picture with a given resolution. And the SDK will render PDF documents into a picture with the desired picture resolution (300 to 600 DPI for high-quality pictures). So you should not worry about the resolution of the source PDF but just need to define output picture size with the same aspect ratio as the source PDF. It allows printing from within the application.

Each of the file formats has its own benefits. JPG files offer adjustable compression with high resolution and smaller file sizes. PNG files may be slightly bigger than JPG but these files have greater compressibility and also supports transparency. TIFF files allow lossless compression which makes it possible to edit and resave without losing image quality. It can also convert PDF to BMP, PDF to EMF, and PDF to multi-page TIFF.

For simplicity, when you are creating a PDF document using tools like PDF SDK (PDF Generator SDK) then these tools are using coordinates calculated using 72 dots per inch (but this can be changed using .Resolution property in the SDK). But, again, this “default” DPI value in PDF Generator SDK tool is just for having a way to comfortably use coordinates to add lines, text, form elements, images (and other object types) and you may create thumbnail or print PDF using any other required resolution and output size.

PDF Renderer SDK is great to use since it renders different fonts with any styling, renders vector graphics as well as images. It works offline and doesn’t require a constant Internet connection. It also does not require any other PDF reader software such as Adobe Reader to be installed. It supports .NET, ASP.NET, and Visual Basic 6 applications with both x86 and x64 mode.

How to change the DPI on a document?

As discussed, the DPI can affect the quality of the output when printing. The settings that will change the appearance of PDF or image output will involve either compressing the file or changing the DPI. Compressing the files can be done right within a PDF reader.

The DPI setting of a printer will relay information to the printing program which has a dialogue box where you can change the DPI settings as well as other parameters. When you go to printing preferences in the printing program, find the advanced settings. Once that is opened you can change the DPI under Graphic-Print Quality before printing the document. On average a DPI of 300 is decent and offers a good quality output and a reasonable file size.

Conclusion

A PDF file is a vector-based file, which does not have a single DPI. Also, you get to have the added flexibility of printing or viewing PDF documents with the best quality. However, the higher the quality of the PDF file, the larger the file, while the lower the quality, the lower the size of the file. Therefore, you have to decide on what quality of PDF file you require and for what purpose.
Furthermore, you always have the option of increasing the DPI of a PDF file. Doing this allows the quality of the file to increase significantly. This conversion can be carried out using the PDF Renderer SDK. Additionally, such a conversion can be done at the point of printing.

   

About the Author

ByteScout Team ByteScout Team of Writers ByteScout has a team of professional writers proficient in different technical topics. We select the best writers to cover interesting and trending topics for our readers. We love developers and we hope our articles help you learn about programming and programmers.  
prev
next