JPG will lose some image quality, which is definitely not desirable for high-quality printed matter. In addition, the resolution is greater than 300dpi, and the color mode is CMYK. Poster advertisements are images printed in TIF format. Although the file is large, the printed poster is more realistic.

And the color mode of the picture must be cmyk, otherwise there will be more serious color difference. This is because the poster printing machine is cmyk four-color printing.

When the designer submits the document for printing the poster, it is best to click on the picture to see whether the picture mode is cmyk and saved as PSD.

Poster printing factory requires 300 pixels/inch for small posters and 80 pixels/inch for large posters.

Common file storage format: 1. If you need to modify this file in the future, please save it in psd format.

Psd format files can retain all layers, masks, channels, paths, non-rasterized text, layer styles and so on. In the document.

2. If the file only needs to be viewed later, it can be saved in jpg format.

3. If the file is set to be transparent, it needs to be used on a web page or flash and saved in png format.

4. If the file moves in time, save it in GIF format.

TIFF, together with JPEG and PNG, has become a popular high-bit color image format.

TIFF format is widely supported in the field of image processing, such as AdobePhotoshop, JascGIMP, UleadPhotoImpact, PaintShopPro, etc.

Desktop printing and page layout applications, such as QuarkXPress and AdobeInDesign, support scanning, fax, word processing, optical character recognition and other applications in this format. Adobe acquired the PageMaker printing application from Aldus and has been controlling the TIFF specification (20 14) ever since.

The term "tag image file format" or "tag image file format" existed as a subtitle in some early TIFF specifications. TIFF6.0, that is, 20 14 TIFF specification, no longer uses these terms, but is called "tiff".

TIFF file format is suitable for file exchange between application programs and computer platforms, which makes the exchange of image data easy.

First of all, when drawing with ps, first make clear a goal, that is, printing, taking pictures, printing or painting. This is the premise of drawing with bitmap software.

For all printed matter, when finalizing with customers, the color mode is preferably CMYK mode, because there is color difference between the drawings in the computer and the actual finished product, and the minimum color difference of CMYK mode is 10%.

Photo: 72dpi, printing: 300dpi, ink-jet printing: 30dpi, if you want to make a large picture of dozens of square meters, you can do 20dpi.