Saturday, April 16, 2016

Vector for Engraving

A lot of our vector drawings are for engravers who tell us they will use the vector file for relief engraving, laser engraving, sandblasting, etching, or cutting. I am guessing these are some of the few process left that require vector art. Although I have never actually used an engraving machine or tool, I have been preparing vector graphics since 2000 for many different purposes including engraving and sign cutting.
Below is a recent engraving project
The image engraved on this stone needs to be reproduced in vector format

This is the vector drawing as per Engraver specifications

Engraver work in progress

Final engraved product

See the project from beginning to end, including errors and corrections that needed to be done before the vector drawing was appropriate for the particular process:

Thursday, September 25, 2014

Photo to Vector Conversion

Manual vectorization with soft color blends

Here is an example of a recent vectorization from photo to vector (raster to vector). This drawing was for screen printing and, for this particular project, it didn't have to be drawn using only vectors. In addition to drawing with vectors, some vector graphics programs also have tools that allow you to use pixel-based, raster (non-vector) elements such as soft color blends & shading/highlights. A graphic that is created with a vector drawing program but also includes pixel-based smooth color blends and soft shading is not a 100% vector graphic, or a true vector graphic; it contains both raster and vector elements. See Raster vs Vector

Photographs are raster graphics made with pixels: a multitude of different color pixels create a realistic image. Vector graphics are drawings made with objects: lines and curves that create shapes. When a photo is vectorized, it means a drawing of the photo is being made and, in most cases, the new vector graphic will be considerably different as you will see in some of the examples below.

Pixels vs Vectors

Raster vs Vector

Manual vectorization without color/shading blends - 100% true vector

Certain processes such as specialty printing (printing on bottles, pens), plotters, vinyl-cut signs, engraving, and other processes require 100% vectors without soft color blends or shading.

Below is a photo to vector conversion with no gradient shading or blends. The original raster and the new vector graphic look considerably different. This project was for engraving which required black and white line art, no gray-scale mid tones. More on Grayscale vs Line Art

100% vector line art

Color "blending" may be created using only vectors by adding multiple objects and gradually changing the color tone of each consecutive object. The more color objects you draw, the smoother the transition between the colors will be. Achieving a smooth transition may be time consuming if drawing is done manually.

vector gradients

Automated vectorization - Tracing tool

A photograph or an image with color blends and soft shading may be vectorized using only vectors and still maintain a strong resemblance to the original. A large amount of color/shade objects may be needed. Rather than drawing each object by hand, the Trace tool in vector graphics program can automate this process. The tracing tool may or may not render acceptable results. In my experience, the same processes that require 100% vector art also require simplified vector graphics with limited amount of color/objects, and accuracy that is often only achieved by drawing manually. See more examples of manual vector conversion vs automated vectorization

Automated vector conversion

Manual vectorization 100% true vector "line art" with color

Below is a raster to vector conversion using only vectors and no pixel elements. The original heart is made of a multitude of different color pixels. The blend of different color pixels gives a 3-D appearance with highlights and shadows. Redrawing the image with single color vector objects instead, produces a considerably different image that looks "flat". Another example of how different an image will look when you take away the color blends. 

100% true vector art

I am hoping the examples above will show how photographs and color-blend-full images may change in appearance when vectorized. See more vector conversions here.

Images were vectorized by Logos and photographs are the property of their respective owners.

I welcome comments and corrections!

Sunday, July 27, 2014

High Resolution Image for Printing

Need a high resolution image for printing?
What is a high resolution image?
Is my image high resolution? And if not, can I make it so?

Common image files such as jpg, gif, png, tif, psd, bmp, are measured in pixels.

The resolution of a pixel-based graphic is the number of pixels within an inch: PPI (pixels per inch)

Whether the image has high enough resolution depends on the process being used. Generally, offset printers (paper printing) require a minimum of 300 ppi, screen printers (cloth printing) require 240 ppi.

In order to determine whether an image is high enough resolution, you need to know 3 things:
  1. Your image's pixel dimensions (e.g 850 pixels wide)
  2. The printed size desired (e.g. want to print a 4 inch image on paper)
  3. The resolution required by the process your image will go through (e.g. printing 300 minimum ppi)

If your image is:
(pixels wide)

It can be printed in good quality at:
(inches wide)















To determine the image's pixel dimensions you will need a program that allows you to do so, such as Paint or Photoshop. Not file size, but rather you need to open the image to see its dimensions.

Your image may look ok on your computer screen (left image), but if it's not the proper size and resolution for your specific printing project, it may print poorly (right image).

If you have an existing image:
To determine what size your existing image can be printed while maintaining good quality, simply divide your image's pixel width by the resolution required by your printer. For example if your image is 850 pixels wide and your printer is asking for 300 ppi: Divide 850 by 300 (850 ÷ 300 = 2.83). Your image can be printed in good quality at 2.83 or smaller. Printing it larger will reduce quality.

Just because an image is very large in pixel dimension and high resolution it doesn't mean it is appropriate for printing. If you take a photo with high megapixel camera and you do something wrong something that is not conducive to good photography happens while taking a photo, you are going to end up with a blurry or poor quality photo that may not print well at any size.

To create the right size image image for printing:
To create an image that will be good enough size/quality for printing (example 300 ppi), multiply the size you want your new image to print by 300 ppi. For example if you want a 6.5 print size, multiply 6.5 x 300 = 1950 pixels, You need to create an image that is no smaller than 1950 pixels wide. A good habit is to always start a little larger than you need (Keep in mind very large files are hard to work with and slow to transfer), you can always reduce to the size needed - you cannot enlarge without losing quality.

How can I increase image resolution? With software like Photoshop you can manually increase the size and/or resolution of an image, but that rarely - if ever - improves quality; you are simply adding pixels randomly throughout the image. If you have a graphic that is not good enough quality for printing, try image vectorization.

Vector Graphics are not pixel-based therefore they are resolution-independent; meaning a vector file can can be printed at ANY size and not lose quality. To see if your image can be vectorized so you never have to worry about size and resolution, upload your image to my

Note: Vector graphics are drawings / illustrations, so the best candidates for vectorization are graphics, logos, drawings, and illustrations, because they can be reproduced in vector format and look exactly like the original or better. Photographs are not suited for vectorization unless you want the photograph to be changed into a drawing.

Saturday, May 31, 2014

Photo to vector for engraving

The only thing I know about engraving is that the vector artwork needs to be created in black and white line-art, and depending on the size of the actual engraving, real small detail should be avoided. There is actually a lot of small detail on the image below and I was sure the engraver was going to reject it but the plaque must have been large enough to hold all the detail. 

Some challenges may arise when changing a multi-color image to black and white LINEART (not black and white grayscale). Elements in the graphic will no longer be defined by different color or shades of gray, they have to be black or white only and you will have to decide which elements are black and which elements are white. Using outlines instead of fills usually works to separate two objects of similar color.

When images are on a color background, removing the background may make the overall feel of the image look different. After playing around with these elements I got a winner.

Monday, May 26, 2014

From Photo to Vector

Here is a recent photo to vector conversion. The project was to change a full color photograph into a simplified vector illustration to be printed using only 3 or 4 colors maximum. (not using the 4 color or full color process but rather 3 or 4 "spot" colors)

The vector file was built with 3 colors: 1. tan, 2. black, 3. red. The gray is a percentage of the black color and can be printed using black ink and "halftone screens". For processes which do not use halftone screens this would be considered a 4 spot color vector illustration: 1. tan, 2. black, 3. red, and 4. gray.

Before online printing exploded as a convenient and inexpensive venue for printing full color, many small printers only had capabilities for printing 1 or 2 color pieces and these were much cheaper than "full color" or "4-color-process" printing. Now most printers can pretty much print anything but there are a lot of processes that still require simplified illustrations with limited amount of colors. Printing on coffee mugs for example (although there are companies like Walgreens that can print a full color photo on a mug), vinyl-cut-stencil-like signs also need limited colors, and the embroidery process are a few that come to mind. Engraving and etching will need black and white only vector graphics - no color.

Sunday, January 13, 2013

Auto Trace vs Hand-Drawn Vector Conversion

Here is a good example of an image that can be vectorized using automated software and it may be acceptable to many customers, yet on closer inspection there is still room for improvement, so for those people whom detail is essential, manual vectorization may be necessary.

 The original raster image is fairly good quality, the pixel dimension is not too small and more importantly there is high contrast between the colors:

See both automated vectorization results and manual vector conversion. At a glance both seem acceptable vector drawings:

But a closeup of the auto-trace results shows some of the detail in the faces is gone. A person with elevated attention to detail will not find this vector conversion acceptable.

Closeup of hand-drawn vector conversion. Note the little noses have a better resemblance to the original artwork:

So taking a few more minutes (or paying a few more dollars) to manually redraw this simple vector image may be worthwhile.

See more samples
20% OFF one vectorization. Code BLOG032013. Only one per customer. Expires March 31, 2013

Saturday, July 21, 2012

Manual Vectorization vs Automated Vector Tracing

To vectorize a raster (bitmap) image into vector format you can either do it by manually drawing node by node using vector drawing software or you can use automated tracing tools within the vector editors. In Adobe Illustrator - which is what I use - the auto-trace tool is called "Live Trace".

Auto tracing is great and almost instant, just a couple of clicks and you are done, so you can save tons of time and money, but automated tracing doesn't work well with all images. It really depends on the original bitmap graphic; the quality, the contrast between colors, even the size. I think the perfect candidates for automated vectorization or auto-tracing are images that are:
  1. Non-geometrical "free flowing" shapes - like the sample tree below
  2. Large, good quality originals that are black and white or high contrast colors with very clear distinction between each color.
  3. Photographs that do not need to be changed to simple line drawings 

The images that will most likely need to be vectorized manually to have a good result, are images with geometric shapes, poor quality originals and images with color blends and gradients. See the difference between auto-traced vs a manually drawn vector graphic:

Samples of photographs vectorized by auto-trace
Samples of photographs vectorized manually and changed to line art
General vector conversion samples