Vectors vs. Bitmaps for Printing

The Difference between Vectors and Bitmaps

First off, we’ll have a quick look at what exactly a vector file and a bitmap file are.

Vector

A vector file is a file that’s constructed from shapes that are defined by mathematical equations. As a result, when you zoom into a vector image, the quality remains sharp, like the image below scaled to 400%.

Vector file at 400% (on screen)Vector image at 400% (on screen)

The fact that vectors are constructed using mathematical equations is their strength. It keeps the details in the image as high as possible, and means that if you want to change how large or how small you would like the image to be printed, you can do so without worrying about quality.

Bitmap

A bitmap file (also known as a raster) is an image that’s constructed from pixels. If you zoom into a bitmap file (like the image below scaled to 400%) you start to see the individual pixels and, consequently, it’s important that bitmap files for of printing are used with a resolution that is high enough — typically, 300 dpi or more.

Bitmap file at 400% (on screen)Bitmap image at 400% (on screen)

The strength of using a bitmap file format lies in the tools you can use to create and edit them (like Photoshop). There are certain techniques that you simply can’t do (or can’t do as well) within a vector graphics editor like Illustrator. This gives you greater flexibility when creating or modifying artwork.

Another strength of bitmaps is linked with their use in photography. Photos are created as bitmaps within a typical digital camera, normally as JPGs or RAW files. So if you’re working with photographic-quality images, you’ll typically need to use a bitmap file.

Vector File Format Examples

Name File Extension
EPS (Encapsulated PostScript) .eps
AI (Adobe Illustrator Artwork) .ai
CDR (CorelDRAW) .cdr
SVG (Scalable Vector Graphics) .svg
PDF (Portable Document Format) .pdf

Note: By the way, PDF and EPS are technically compound file formats, meaning that they can handle both vector and bitmap artwork. However, for simplicity’s sake, they’re more commonly known and categorized as vector file formats.

Bitmap File Format Examples

Name File Extension
TIFF (Tagged Image File Format) .tif, .tiff
JPEG .jpg, .jpeg
PSD (Photoshop Document) .psd
GIF (Graphics Interchange Format) .gif
PNG (Portable Network Graphics) .png

Visual Comparisons of Vector vs. Bitmap

300 dpi is generally considered the minimum resolution for printing bitmap work, like photos or complex artwork.

There can be a marked difference between the way bitmaps and vectors are printed.

Below are some close-up images from a chapter on file types in The Print Handbook. The book was printed using a Heidelberg Speedmaster XL75 litho printer. Each image’s actual width is roughly 15 mm (just over half an inch).

EPS and PDF (PDF/X 1a:2001)

Here are two examples of an EPS image and a PDF image.

EPS visual exampleEPS example

PDF visual examplePDF example

You can see that there’s no noticeable difference between an EPS and PDF. They both produce sharp results.

TIFF (300 dpi)

Here is an example of a TIF image.

TIF visual exampleTIFF example

This is where things start to get interesting.

Even at 300 dpi, a TIF cannot produce the same quality as a vector file. Through the process of converting the original Illustrator file to a TIF, the smoothness of the lines is lost. It’s possible to see the individual dots of the print screen, which disrupt the crisp edges of the lines.

It’s worth noting that, though the images here are close-up images, the difference is still noticeable to the naked eye.

JPEG (300 dpi/Quality: High)

Here is an example of a JPEG image.

JPEG visual exampleJPEG example.

The JPEG image above (with its quality set to High) struggles like the TIFF. The lines seem rough and the dots of the print screen are again visible.

Another issue with the JPG image is the white in the original image is no longer white. The spaces between lines have been filled with a compression noise that the TIF does not have.

One last problem that occurred with the JPG was its inability to reproduce spot colors. The red lines in each of the previous examples are printed using Pantone 185. However, JPGs can;t work with spot colors so this was converted to a CMYK value instead, which produces a color that is a little yellower.

Summary

After comparing various vector and bitmap images, I think we’ve learned a few things.

  • Vector files like PDFs and EPSs produce the sharpest printed results, even when compared to a 300 dpi TIFF.
  • One thing to bear in mind in all this is that the lines within the artwork are made up of solid colors (e.g. 100% cyan). This means that no print screen dots can be seen on the vector example photos. However, if the lines were tints (e.g. 50% cyan) then dots would be seen on both the vector and bitmap artwork to create the illusion to the naked eye of a lighter color. As a result, the difference in print quality between the two types of file is likely to still be there, but less obvious.
  • If you’re using spot colors in your artwork, then avoid JPGs. They can’t handle spot colors and will simply convert any spot colors to CMYK or RGB.
  • If you’re creating a bitmap file, then save the file as a TIFF or PSD to keep the full amount of detail. We’ve seen above that even a JPEG saved at High quality still loses detail.
  • Ultimately, there are certain situations (like working with photographic-quality images) where bitmaps are your first choice; but if you can, use vector files whenever possible.
  • gez

    You’re missing an important fact: The RIP (which by the way means ‘raster image processor’) converts those vectors to high resolution bitmaps. So you’ll be printing bitmaps anyway.
    The difference is that bitmaps @300dpi are (likely) kept at that resolution while vectors are rasterized using much more resolution and no antialiasing.
    The dithered edges in your samples are caused by antialiasing, not low resolution.
    I’d say the worst problem of working with 300dpi tiff files with vector shapes or text is that. The AA pixels aren’t solid colors, so they’re dithered by the RIP (just as any 50% black shade, for instance). So, avoid antialiasing and you get sharp edges.

    What happens if you print a 1200 dpi tiff image (without antialiasing) created from the same vector shapes? You get something that looks pretty close (if not exactly) to the prints produced from vectors.
    Even 600 dpi without antialiasing will look pretty similar if paper has a moderate dot gain.

  • Russell Spears

    But 1200ppi Tiffs are large files at any reasonable size. I do not believe JPEGs are as bad as shown when compared with tiffs if the least amount of compression is applied. As far a vector, if your careful with the color build, you can get great line work. Anyone else want to weigh in on Jpeg files VS Tiff Files?

  • Di

    Do not say to work and print vector is always easier and more efficient, add at least 600 DPI, but will be a little confusing – if card =). For the article thanks!

  • Very nice comparision.

  • Russell Spears

    You should show what comes out of a RIP system that is raster type at 300 and 1200. and compare it to what comes out from vector. Then you will see the difference.

  • This is a very well written article. It’s incredible how many want-to-be graphic designers at their young careers do not understand this whatsoever at a deep level. This is graphic design 101. I’m 26, with young eyes – I can tell without a microscope when letters/shapes are printed from a bitmap rather than vector. I can see the edges, and the perceptive quality diminishes very quickly if that is the case.

  • SANJEEV

    CAN YOU THINK OF FOUR COLOUR PROCESS IMAGE WITH CONTINOUS TONAL VALUE BEING PRINTED WITHOUT ANY PIXEL DOTS.

  • This article is so interesting and informative.

  • Excellent comparison….between Vector vs. Bitmap.

  • Laura

    dumb question then… 8 ft banner. combination of text and photographic images. I am torn about how to best handle this. Clearly I’d prefer to build the majority of the file as vector and add the images as bitmap. My guess is that this is either a silly concern OR that I should just do as I always have and design as high res as possible and send to printer as a pdf. Nervous about the scale and quality loss.

  • Alain Godfried

    GEZ is correct (1st comment), and no Jeff Kee, you are NOT able to tell the difference between a printed bitmap or vector if the ‘bitmap’ is correctly done for printing (i.e.: high-res & no-aa).
    It’s funny how people think that printing vectors somehow activate a ‘magical’ mode in which the printer has twice the resolution or something… This makes no sense whatsoever.
    Fact 1: Ultimately, the printer is a ‘raster’ device.
    Fact 2: Anti-aliased edges are ‘dithered’ by the printer, resulting in what seems a low-resolution edge, but in fact is a representation of ‘intermediary’ colors.
    Once you understand the basic concepts behind AA, pixel/dot density, and the comment by GEZ, you’ll be able to achieve a vector-like print quality from bitmaps.

  • Rick

    I just started my journey into graphic arts and what I’m confused about is how does a vectored piece of art get printed from a commercial printer. I sent an .AI file via email (FTP)to a commercial printer and they had trouble with the file. She could see what I sent in the window but when she tried to print the image she got a warning prompt. What is happening here? Does it need to be converted to a PDF, and if so, will I lose my ability to blow my image up to poster size and not suffer resolution quality; which seems to be the whole point of printing it as a vector file.

    How is it possible to have a very graduated value in my image unless it is a rasterized image?

  • Timmie

    So far so good.. I gained a valuable lot today.. Can i still get a print preset using either postscript or pcl 5 for my bitmapped coreldraw files? 🙂
    Thanks yall..

  • Paul Jones

    There is one process which can emulate full tonal ranges without the need for screens and dots. It’s called a Collatype machine (check it out) and uses a gelatine type base transfer of image. It’s very expensive and is mainly used for short runs of high end art books for example where original colour and tonal ranges are paramount. It’s very rarely used in commercial art repro work. Hope this helps. As far as I know this is the only process capable of reproducing continuous tone ranges repeatedly.
    All the bestPaul Jones