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Image files submitted for print must have an effective print resolution of at least 300 pixels per inch (ppi). IDoPrint.com's preferred print resolution is 350ppi. We print at a line screen of 175 lines per inch (lpi). Printing at a higher line screen produces cleaner, sharper images. Most online print vendors print at lower screen values of 133lpi to 150lpi. The ideal image resolution for printing CMYK, sheet fed offset is calculated by multiplying the halftone screen value by two. Using that formula the ideal image resolution for 175lpi is 350ppi. Images saved at 300ppi, although not ideal, will print just fine.
Please be sure that your images are not scaled in such a way as to push their effective resolution below 300ppi. There is a fixed relationship between and images pixel dimension and it’s effective print resolution. To illustrate the relationship between pixel dimension and resolution, consider an image with a pixel dimension of 600 pixels x 600 pixels. If we set its size to 2” x 2”, the image’s print resolution is 300ppi.The relationship is fixed. Any change to the image’s size changes its print resolution. Increasing the 2” x 2” image to 4” x 4” decreases its print resolution to 150ppi. Conversely, decreasing the image’s size by 50% increases its print resolution to 600ppi. Be careful not to scale cmyk or grayscale images to a size that would make their print resolution less than 300ppi.
Digital cameras differentiate resolution settings by pixel dimension. A digital camera may offer photo resolutions like 1600 x 1200 or 600 x 800. To determine the maximum size a digital photo may be printed simply divide each number by the required print resolution.To achieve the required 300ppi, a digital photo taken at 1600 by 1200 can be printed at 5.3” x 4” or smaller. (1600pixels/300ppi x1200pixels/300ppi).
For an illustrated and detailed discussion of image resolution along with a resolution calculator, please go to: Monochrome Images (1-bit) intended for offset print should have a print resolution of 800-1200ppi. In general, monochrome image resolution should be equal to the resolution of the intended output device. Output resolution for computer-to-plate devices is typically about 2400dpi. However, no signficant difference can be visualized when 2400ppi and 1200ppi monochrome images are compared. So, the target print resolution for monochrome images is considered to be 900-1200ppi.
CMYK and Grayscale (8-bit/channel) images intended for offset print should have a print resolution of 300ppi.This recommended resolution, as well as ranges suggested for other file types, assumes that the images will be printed at 100% scaling or less. See the Image Resolution section for further details.
Multi-tone images combine 1-bit and 8-bit elements.They contain text and line art components along with cmyk/grayscale data.Text and line art will appear jagged when printed at 300ppi. Because, higher resolution equates to larger physical file size, making the file1200ppi to satisfy the type or line art, produces a monster file. So for multi-tones, a compromise is achieved at 600-900ppi that balances the issues of aliasing and physical file size.
For an illustrated and detailed discussion of image resolution and color depth please go to: http://dx.sheridan.com/advisor/image_resolution.html
Products on IdoPrint.com are printed using the CMYK process. Files submitted must be in CMYK color mode. If your files are submitted using any other color model, such as RGB or Pantone, they will be converted to CMYK. Converting from one color model to another may cause un-expected color shifts.
Monitors do not always accurately represent how your colors will print on paper. Your computer’s monitor uses RGB to represent color. RGB has a much wider color gamut than CMYK. Therefore, there are colors your monitor can render that cannot be printed using CMYK. Pantone colors may also not convert well to CMYK. Pantone (PMS) inks are premixed inks that use a wide variety of pigments outside the CMYK gamut. Some PMS colors convert fine when printed in CMYK. Others like metallic gold, metallic silver, reflex blue, or fluorescent have no corresponding CMYK equivalent.
For more a more detailed explanation of cmyk color theory please go to. http://dx.sheridan.com/advisor/cmyk_color.html
A large solid area or large block (k) type will not print black if simply created using 100% k. It will appear as more of a dark gray. To print a nice dark, rich, black, please make your blacks, 60 cyan, 60 magenta, 60 yellow, and 100 black. Be careful that all of your supporting graphics have the same black specified. Different blacks, although barely noticeable on screen, will appear very differently when printed. Black type greater than 18 points and solid black areas greater than an inch square should be specified using the formula above.
Bleed Artwork If your artwork is going to print right to the edge of the page, you need to extend it past the page boundary by at least .125”. The extended artwork is described as bleed and will be cut off when the work is finished. Bleed serves an important purpose. Your artwork is printed and finished on large mechanical devices with some tolerable variances. The image may bounce or move a bit from sheet to sheet. Your job will also be cut on a large hydraulic guillotine cutter. As hard as we might try, it is impossible to stack the sheets exactly on top of each other to make the cut. The extended image insures that no white space will appear when the work is trimmed and finished.
Live Area Please be sure to keep any text or graphics that must not be cut off, to .125” from the edge of the sheet. The .125” safety zone may be trimmed off when cutting. Your artwork is printed and finished on large mechanical devices with some tolerable variances.The image may bounce or move a bit from sheet to sheet. Your job will also be cut on a large hydraulic guillotine cutter. As hard as we might try, it is impossible to jog the sheets exactly on top of each other to make the cut. Keeping important images and graphics in the safety zone insures that nothing will get in the way of your message.
A gradient is the transition of one or more colors from dark to light. They are very often used in printing and work well as design elements.They become problematic when the color varies too little over too large a distance or when the gradient ends in less than 5 percent of a color. Gradients without sufficient variance between the light and dark color may appear banded when printed. Banding can be completely avoided be creating gradients in Photoshop and adding noise. The noise disperses the dots, minimizing or eliminating banding.
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Print File Preparation Guidelines
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