Professional Tips for Converting BMP to DXF

Updated Jun 1, 2018
Pro Tips Convert BMP to DXF

In design and engineering, raster images like BMP can be rather problematic: they lose quality when scaled, and they cannot be edited using CAD software. To avoid these issues, users can convert their BMPs to a vector format like DXF instead. This conversion process usually involves manual tracing, or automatic tracing using software like Scan2CAD. 

This guide will tell you everything you need to know about BMP and DXF files—plus, we’ll show you how Scan2CAD converts between the two formats in a few easy steps. 

Table of Contents

What is a BMP file?

image of a bmp icon The BMP file format is the native file format of the Windows platform. It is used for storing two-dimensional digital images in various color/bit depths. The BMP file format is sometimes also known as DIB, or device-independent bitmap. Its main virtues are its simplicity and widespread support in the PC marketplace. Virtually every program can open and save images to the BMP file format.

As you might have noticed, the bitmap file format is not commonly used on the web. This is because they are uncompressed and relatively large in size. Bitmap images can use a compression method called run-length encoding (RLE), however this is rarely used.

How do I store an image in BMP format?
If you’re scanning a sketch, you can instruct your scanner to save the image using the bitmap file format. If you’re drawing an image on graphic software like Photoshop or Paint, simply choose the BMP format in the usual ‘Save As’ dialog box.

As BMP files faithfully display raster images with no loss of quality, they are a good choice to use when converting your image to vector. Other useful formats for this purpose include TIFF and PNG, both of which support lossless compression. These are just a few of the 33 different file formats which Scan2CAD supports.

It’s worth noting, however, that you don’t need to convert your raster image to BMP prior to conversion. If you’re using a suitable format, such as TIFF or PNG, then converting will likely give you a larger file size with no increase in quality. Meanwhile, if you’re using an unsuitable format for vectorization, such as JPEG, then converting won’t fix any issues with your image, as data loss will have already occurred.

NB: The term “bitmap” can also refer to a raster image. Any image that uses pixels on a fixed grid to define an image can be called a bitmap. That’s because these images are literally a map of bits. The term “raster images” refers to different file formats, such as JPG, GIF, PNG as well as BMP. In this post, we’re discussing the BMP file format.

What is a DXF file?

DXF icon DXF, or Drawing Exchange Format, is a vector graphics format primarily used in computer-aided design (CAD). It was created by Autodesk to serve as an exchange medium between different CAD programs. 

DXF is an open standard, and is supported by almost all CAD programs on the market. You can view DXF files using a range of programs, including AutoCAD, Adobe Illustrator, and, of course, Scan2CAD. This wide support means that DXF is the lingua franca of the design and engineering industry—facilitating collaborative editing. DXF stores the design information in mathematical instructions called vectors, so that it can be easily scaled and edited.

Why convert BMP to DXF?

In a nutshell, BMP files are raster images, which cannot hold the information required for CAD design. Due to this, users would need to trace their BMP if they wanted their design in CAD format. Tracing can be done manually or automatically with conversion software like Scan2CAD. After converting the image to DXF format, you can load the image into any CAD software and edit it, or even copy certain elements for use in other drawings.

Secondly, BMP files cannot be rescaled without losing definition. All image data is saved in pixels (tiny blocks of individual color)—try resizing it or zooming in and you’ll notice that the image looks blurry and pixelated. In comparison, a vector image saves the design in the form of graphic coordinates called vectors. This data is not dependent on the resolution—so after you convert the BMP image to DXF, you can increase the size without losing any quality. For more information, check out our article on rasters versus vectors!

Not sure which vector type to convert your BMP to? This handy reference may be of assistance. 

CAD Drawing DXF File - Architect Example

Case study: Once the scanned floorplan (left) is converted to DXF format (right), it becomes useful for various project members. An engineer may use the floor plan for electrical wiring while the interior designer uses it to visualize the space

Why should I use BMP over JPG?

Most images are saved and shared in the JPG format—so why not convert JPGs to vectors? Well you could, but that would be ill-advised. In fact, you might have come across the oft-quoted piece of advice: avoid JPGs and GIFs when it comes to vectorization. This is because JPGs become blurry and undefined when scaled or resized. Worse yet, this file format also uses lossy compression, which means that the image loses quality when edited in order to keep file sizes down. 

The best course of action is to use BMP or TIFF images instead when you want to convert a raster to a vector. This is because these file formats use lossless compression and encode every single bit of information when saved. They’re typically a little larger in file size, but it’s worth overlooking this downside due to the vastly improved quality of these formats. 

To learn more, check out our article on different raster file types.

How do I convert a BMP file to DXF with Scan2CAD?

1. Load your BMP in Scan2CAD. This works the same as opening a file in any program. Just click FileRasterLoad, and select your BMP. 

2. Choose your settings. Scan2CAD has a range of vectorization settings which are specialized to deal with specific image types. Use the Type menu to select the appropriate settings for your image.

3. Convert your image. You can either click:
vectorization button screenshot  :  which converts lines, curves and shapes to vectors.
OCR button screenshot  : to convert raster text to vector text.
All button screenshot  : which converts the entire image (both lines and text) to vectors.

4. Save file as DXF. Just click FileVector Save As. 

After converting your BMP to DXF, you will be able to open your design in any CAD application.

Clean, Convert and Edit With Scan2CAD

Don’t convert without reading these tips first!

Remember: garbage in, garbage out
It’s important to choose the right BMP image for conversion—and to ensure that you’ve optimized your image. You can use our Raster Quality Checklist to avoid the common problems in raster image conversion, such as choosing an image with too many colors and too much noise or speckles. Making simple changes like straightening a skewed image and cropping unwanted details can also go a long way in optimizing your image.

Poor image quality for raster to vector conversion

Don’t bother converting any raster image that sports any of these problems…

Beware of free online converters
Some free online converters only create DXF files with an embedded image—instead of tracing the raster image using vector elements. Others produce shoddy results with simplistic vector types, or no OCR and so on.
Automatic conversion software can only deliver a 95%-ready DXF file, at best.
Depending on your application, you may want to edit the vectors. For example, CAD files for CNC require you to join vectors into a single tool-path, convert Beziers into polylines, change scale and remove unwanted vectors.

Scanned PDF to DXF to uploaded for editing with CAD software: PDF to DXF File Conversion

Scan2CAD comes with a complete suite of raster and vector editing tools

This article forms part of our Ultimate Guide series. You can also check out our articles on how to convert to DXF from TIFF, PNG, PDF, JPG or DWG.

Scan2CAD is the market-leading ultimate vectorization software. It supports 33 different file types and comes with a full raster and vector editing suite. Not to mention, its powerful batch processing capabilities, and its Smart OCR. Try out all of Scan2CAD’s features for yourself, with our 14-day free trial. There are no limitations to this trial—you can convert as many files as you want; no restrictions, no watermarks. Just click the button below to start your download now. 

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