Printing factory's requirements for images in documents [Buke printing] to tell you

Printing factory's requirements for images in documents [Buke printing] to tell you

The requirements for images in printed documents are reflected in four aspects: file format, color mode, bit depth, and resolution. Further requirements include color, layering, and image quality.

The basic requirements of printing factories for documents include file format, color mode, bit depth, and resolution.

Please use Photoshop to open various image files on your computer and view the following items:

1、 File format: In the title bar of the document window, you can see that the suffix of the file name is the file format.

No matter how many formats the original manuscript has, when it comes to publishing, there are only three options: tif, eps, and pdf. TIFF is the most commonly used. Scanned images of various original manuscripts, images copied from libraries, online images... can all be saved in TIFF format. The production folder of a design company is often a layout file with a bunch of tif images. If there is EPS or PDF, it is also possible, but not JPG, GLF, PNG, etc., as their output effect is unpredictable.

There are special reasons for using EPS or PDF:

The first reason is to create a vector diagram.

The second reason is to combine vector graphics and bitmap into one file.

By doing this experiment, you will immediately understand what vector and bitmap images are: open a photo like image in Photoshop, input some text without rasterization or layering, then save it as PDF format, open it with Acrobat Reader, zoom in and out again, and you will find that the background image is blurry and the text is clear. This file contains both bitmap and vector graphics. The base image is a bitmap that becomes blurry when enlarged, while the text is a vector image that remains clear no matter how many times it is enlarged. If this PDF is taken out, the resolution of the text can be increased arbitrarily, but the base image cannot. The same goes for saving in EPS format.

Pure bitmap can also be saved in EPS or PDF format, but there is no need for it. Saving a photo in EPS or PDF only increases the time for saving and opening. EPS or PDF can only maintain the vector properties of a vector image, but cannot convert a bitmap into a vector image. Just save the photo as tif.

2、 Color mode: View which color mode in the "Image>Mode" menu in Photoshop:

The color mode is a way of describing colors by dividing them into certain components. The RGB mode describes the content of the three primary colors of red, green, and blue in colors, while the CMYK mode describes the proportion of four inks: cyan, magenta, yellow, and black. No matter what mode the original manuscript is in, it must be converted to one of the following modes: CMYK, grayscale, black and white binary.

For four-color printing, CMYK mode is used. For monochrome printing, use grayscale mode. There is a special case in monochrome printing, such as mechanical structure diagrams, which only require 100% ink to print lines and color blocks without the need for screening. This type of diagram can be printed in black and white binary mode.

3、 Bit depth: Check under the "Image>Mode" menu in PS, which bit/channel is it.

In a color space, there can be 2n colors called n-bits, and the black and white binary mode is 1-bit because there are only 21 colors - pure black and pure white. There are three options for other color modes: 8-bit/channel, 16 bit channel, and 32-bit/channel.

4、 Resolution:

The resolution of the prepress image should be at least 300dpi. But if the logo pattern and text must be made into a bitmap, it is best to have a resolution of at least 600dpi to ensure clear output. If the color model is black and white binary, the resolution should be higher. For images on the internet at 72dpi, if the size is not reduced but raised to 300dpi, it will become very blurry.