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VECTOR vs. RASTER- The Resolution Issue

You'll want to use your new logo in a variety of sizes - some small, some large. This won't be a problem with the VECTOR formats we provide you. Since VECTORS are based on mathematical equations - they can be used at any size. VECTOR file formats always output at the highest resolution of the device you're using to print with, so you'll always be assured of the best reproduction quality available.

RASTER or pixel based images are a different issue. Because they are created using tightly packed pixels, these images (.JPG, .TIF,. .GIF) must be in the resolution of the device that they're being used on. On a monitor that equates to 72 dpi (pixels or Dots Per Inch), but in print that requirement balloons to a minimum of 266 dpi. RASTER images should not be enlarged as the pixels will become visible. Simply changing the print resolution of a 72 dpi image to a 266 dpi image will NOT address this problem. To get around this, simply scale your VECTOR image to the size required, and create a RASTER image from that.

Any form of electronic reproduction (except for Flash designs and animations) requires RASTER images such as .GIF and .JPG. Because of the way they're created, RASTER images lend themselves to special effects more readily. Also, many office software products utilize RASTER images to import artwork. You still need RASTER versions of your new logo, but these should always begin life as your VECTOR image.


Resolution for Raster Images of your Logo

Resolution is a measure on how compact you store the data of an image. Depending if you are going to display your logo on the screen or if you want to print it, you use different resolution. 

Screen

If you are going to display your logo on the screen you should always use 72 dpi, unless you want to be able to resize it.

Printer

In order to determine the resolution for your logo you need to know which printer you are going to use. To store your logo in a higher resolution than the printer can print is pointless. 

To scan an image in higher resolution than 300 dpi (Dot Per Inch) is for example in most cases unnecessary if you are going to print the image on an ordinary laser printer. The image quality will not improve in printing; it will just take longer to print.

Black & White Images

Images that just contain only black and white dots should in most cases be scanned in 600 dpi to obtain a good quality. The exception is if the files become too large to handle, 300 dpi is in most cases acceptable. 

The table below displays the file sizes for uncompressed black & white images in different resolutions. For more information, see Compression

Purpose Low Quality
72 dpi
Mid Quality
300 dpi
High Quality
600 dpi
Images 10*15 cm 0,02 MB 0,26 MB 1,00 MB
US-Letter 0,1 MB 1,3 MB 5,2 MB

Suggested resolution for different media types/printers.

Media Suggested resolution (dpi)
Screen 72
Laser Printer, 600 dpi 600
Print 600

Grayscale Images

Grayscale images are images that contain different levels of gray to represent photos etc. It is just like a color photo, just without the color information. 

The resolution for grayscale and color images is set by the printer's resolution. The Line or Halftone Resolution is a measure on how many rows of groups of dots a printer can print. A rule of thumb is to use a resolution that is twice (X2) the Line Resolution.

The table below displays the resolution for grayscale images. 

Media Printer's Line-resolution
(LPI - Line Per Inch)
Suggested resolution (dpi)
Screen   72
Laser Printer, 600 dpi ~60 120
Print ~133 266

The table below displays the file size for uncompressed grayscale images in different resolutions. For more information, see Compression. To store a grayscale image you usually need 8 bits to save a 256-color image. This is in most cases enough for a good image quality. 

Purpose Low Quality
72 dpi
Mid Quality
300 dpi
High Quality
600 dpi
Images, 10*15 cm 0,1 MB 2,0 MB 8,1 MB
US-Letter 0,6 MB 10,4 MB 41,8 MB

As you may have noticed, the file size of a grayscale image is 8 times an black & white image. 

Color Images 

A color image is just like a grayscale image but every dot includes a color value. Since a monitor is using three colors; red, green and blue, the images are usually stored in these three colors. This requires three times as much storage space as a grayscale image. 

To get that good quality, color images should be saved as 24-bit color. This means 16 million combinations that can be shown. Screen shots usually only require 256 colors. These images only require one third of the full color image. 

The table below displays the file size of uncompressed 24-bit color images in different resolutions. For more information, see Compression. Color images for print are rarely scanned with higher resolution than 200300 dpi, unless you want to resize them.

The table below displays the suggested resolution for color images. A rule of thumb is to use a resolution that is twice (X2) the Line Resolution (LPI). The Line Resolution is a measure on how many rows of groups of dots a printer can print. 

Media Printers Line-resolution 
(LPI - Line Per Inch)
Suggested resolution (dpi)
Screen   72
Laser Printer, 600 dpi ~60 120
Print ~133 266

The table below is displaying the file sizes for uncompressed grayscale images in different resolution. For more information, see Compression

Purpose Low Quality
72 dpi
Mid Quality
300 dpi
High Quality
600 dpi
Images, 10*15 cm 0,35 MB 6,1 MB 24,4 MB
US-Letter 1,8 MB 31,4 MB 125,5 MB

As you may have noticed, the file size of a grayscale image is 24 times an black & white image and 3 times a grayscale image. 

If you are working with images on professional bases and you want to absolutely sure that the colors are perfectly matched you might want to store your images in CMYK mode. 

The CMYK model stores the information as Cyan, Magenta, Yellow and Black instead of RGB - Red, Green and Blue. Most professional printers use the CMYK model. If you use the RBG model which is the most common, the images will automatically be converted into CMYK mode in the printer process. The file size for a CMYK image is 1/3 larger than a RBG image.  

File Size

The basic formula for the file size is for an image is:

File Size (MB) = (Height in Inch x Width in Inch x Bit depth x dpi2) / 8

The reason to divide by 8 is that one byte is eight bits.

Bit depth

The table below shows the tones for black & white, grayscale and color images.

Purpose Bits Tones
Black & White images 1-bits color 21 2 tones
Color, Grayscale, Index 8-bits color 28 256 tones
True Color 24-bits color 224 16,7 million tones
  32-bits color 232 4,2 billion tones

 

Scaling

As we discussed the smallest part that can be displayed is a colored dot, a pixel. 

Resolution (dpi) = (No of Pixels) / (No of Inches)

You can easily see if you want to double the size in inched the resolution will go down to half. 

The relation is very simple. If you want to reduce the size three times you can scan the image in 1/3 of the expected resolution. 

A 5-inch/cm photo that you want to print in 20 inch/cm on a 200 dpi printer should be scanned in 800 dpi to compensate the lack of data. 

International Standard Paper Sizes

Size

Millimeters

Inches

US-Letter

215.9 x 279.4

8.5 x 11

US-Legal

215.9 x 355.6

8.5 x 14

A0

841 x 1189

33.125 x 46.75

A1

594 x 841

23.375 x 33.125

A2

420 x 594

16.5 x 23.375

A3

297 x 420

11.75 x 16.5

A4

210 x 297

 8.25 x11.75

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