We recommend saving your print files as PNG. PNG allows you to preserve transparency,  maintains resolution, and is a modern, universal format. 
 
To save your print ready images in Photoshop or Paint, go to File > Save As > PNG. In Illustrator or Draw,
you must export your image, go to File > Export > PNG.
 
If you are creating your own artwork in a raster program always ensure you have a transparent background layer.
A transparent background looks like a white and grey grid. If you see a white or colored background and you do not see the transparency grid,
your printer will print the solid background on dark garments.
 
When exporting from a vector program, size the artwork to the approximate print dimensions,
and export as .PNG at 300dpi.
 
RGB is an additive color model where Red, Green, and Blue light is added together to form a color gamut.
RGB input is typically used on most all electronic devices, TV, Computer Screens, etc. RGB offers a larger color gamut than CMYK.
 
CMYK is a subtractive process requiring a white background using 4 colors, Cyan, Magenta, Yellow, and the Key (black ink).
CMYK is the standard process for most all common digital printing processes. Most direct to garment printers, such as the Epson SureColor F2000, print with CMYK + White ink.
 
Even though your printer prints in CMYK, its best practice to design in RGB for all print applications for the following reasons:
 
- CMYK file sizes are about 25% larger than RGB.
- Most filters and image enhancements are only available in RGB color mode.
- Web art and most printers require RGB color mode so there is no need for conversion from CMYK.
 
Matthew Rhome, DTG Business Development, Fabric Imaging for Epson America, helps explain CMYK printing and RGB artwork:
 
“The Epson SureColor F2000 DTG Printer is specifically designed to enhance the CMYK color gamut to achieve as close to the RGB spectrum as possible. Because of this, the SC-F2000 offers some of the industry’s most vibrant color values”.
 
The Epson SC-F2000 is a perfect example, the Epson F2000 accepts (SWOP2 standard), however we don’t generally recommend it as there is no support for transparency in CMYK data (For Garment Creator).
 
Now because we are working in a vibrant spectrum like RGB, let’s talk about some functions you can use to optimize your artwork for maximum quality.
 
This list below was given to me by Great Dane Graphics and is set up for use in Photoshop; all of the functions should available in Corel Paint or similar raster image software. I highly recommend following these instructions for all your photo based artwork before you print.
 
1 In Photoshop go to Image > Adjustments > Selective Color. Change the “Colors” pop-down menu to “Neutrals” and change all the values to between 3-8.
 
2 Go to Image > Adjustments > Hue/Saturation and move the Saturation slider to the right. It can typically be moved to anywhere within the 0-45 range. Move it to the right as much as needed to saturate your colors without becoming over saturated and flat.
 
3 Go to Image > Adjustments > Brightness/Contrast, and move the Contrast to 5. If you have a newer version of Photoshop you will see a “Use Legacy” check box, be sure to check it on.
 
4 Next go to Image > Adjustments > Levels. Holding down your Option Key, move the black slider on the left side of the Input Levels to the right until you see black pixels show on your screen. Then move the white slider on the right side to the left until you see white pixels show on your screen. By doing this you are setting your black and white points in your image, and helping to reduce any “muddiness” in the colors of your layout.
 
5 Go to Image > Mode > Lab Color. Open your Channels palette and click on the Lightness channel to select it.
 
6 With the Lightness channel selected, go to Filter > Sharpen > Unsharp Mask. Move the amount slider to the right. We can really increase the sharpness because we are only working with the luminosity of our image, not the color.
 
Recap of preparing a perfect file for direct to garment printing
 
- Create high resolution artwork at 300dpi/250dpi, or 72dpi with extremely large image dimensions.
- Save artwork from Photoshop or export from Illustrator, to ensure transparent background, PNG preferably.
- Design or convert artwork to RGB if already CMYK.
- Follow the instructions for pre-printing file optimization.
 
TIPS for dgt
 
White Transparencies on DTG
 
Here is a spectrum of different percentages of opacities of white ink so you can visualize how it will print.
Our recommendation would be that you stay above 30% opacity, as you can see it is barely visible at any percentage lower than that.
whitetransparency
As you can see, any transparencies lower than 30% are either super faint or don’t show up at all – keep that in mind when designing!


On white Garment printer not print white color on black garment the printer not print black color.

 
BlackInk on DTG
 
Although the true black is usually #000000, achieving this on our DTG printers is a bit different.
The way to get a nice dark black, especially on lighter garments, is with the CMYK values 55,55,55,100, respectively.

WHITE ON DARK GARMENT

You can try with add 2% to cyan for obtain better white print.

 
Other information dgt print information:

https://blog.threadless.com/dtg-faq/
https://www.sharprint.com/blog/bid/103824/5-Art-Elements-to-Avoid-when-DTG-Printing
https://blog.bellacanvas.com/5-questions-dtg-direct-garment-answered/

Specify for our printers

Color Space:  sRGB
Color Mode:  sRGB. CMYK (not for png), grayscale, 
File Type: png (8bit not compressed or intralaced)
Resoluition: Up to 360dpi