Print Photos with GIMP and with gThumb

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Printing Photos with GIMP and with gThumb

NOTE: This how-to is based on Linux Mint 17.3 Rosa 64-bit, Xfce 4.12.2 desktop, GIMP 2.8.10, gThumb 3.2.7 and HP PSC-1350 printer. The photos are printed on 4 inch x 6 inch paper. The printer configuration can be preset if you like by: LM menu → System → Printers then double-click HP PSC-1350 (choose your photo printer if different). Set Printer Options:
Media Size: Photo 4x6in
Double-sided printing: Off
Media Source: Auto-Select
Media Type: Photo Paper
Print Quality: High-Resolution Photo or Normal Color if no Photo cartridge
Installed Cartridges: Photo and TriColor or Black and TriColor if no Photo cartridge

Printing a Photo with GIMP

Start GIMP and load your photo with File → Open. From the GIMP menu bar choose Image → Scale Image. With the ratio chain connected, change the X Resolution to 300.000 then click in the Y Resolution box and it will automatically change to 300.000. (The ratio chain is to the right of the X and Y Resolution boxes. If you click it, it will open. Clicking it again will reconnect it. We want it connected).

We also keep the ratio chain for Width and Height connected. To the right of this chain, change the units selection to 'in' for inches. Set the Height to 4.000 then click in the Width box and its value will change to a value close to 6.000. It may not be exactly 6.000 because the connected ratio chain preserves the proportions of the picture. You could open the ratio chain and set the value to exactly 6.000 but the printed photo will be either somewhat squeezed or stretched.

Set the Interpolation to 'cubic' then click Scale. Your image will be redrawn on the screen and it will be ready for printing. CAUTION: do not click File → Save because that would overwrite your original file! You could do File → Save As… to create a new file with a different name. For simply printing a photo, saving the scaled image is not necessary.

Click File → Print in the GIMP menu bar. Choose your photo printer if you have more than one printer connected. Check the print dialog tabs to see that the settings you made earlier are there. Make sure the Orientation is set to Landscape and that Image Quality is High Resolution Photo if you have a Photo cartridge installed in the printer. Image Quality should be set to Normal Color if a Photo cartridge is not being used.

When quitting GIMP it will tell you that there are unsaved changes. Closing GIMP without saving the changes will leave your original file untouched.

Printing a Photo with gThumb

Follow the same printer configuration as noted before.

Start gThumb and navigate to the folder containing your photos. If gThumb is new to you, choose Help → Contents → Browsing Your Files for an overview. Click the thumbnail of the photo that you wish to print. Then click File → Print and choose the printer to be used.

In the Print dialog click the Page Setup tab and verify that the settings are as intended above and that the Orientation is Landscape. Click the Images tab and note that a Header or Footer can be printed if desired. The image will shrink to accommodate either or both. In the bottom of the Images dialog is a Position box followed by a choice of Centered or Custom. You can choose Custom and move the image so it is flush with one side of the photo paper if you like. Leave the Size slider set to 100%.

Click the Image Quality tab and choose High-Resolution Photo if you have the Photo cartridge in the printer. Choose Normal Color if the Photo cartridge is not being used.

Click the Advanced tab and choose Photo and TriColor if you have the Photo cartridge in the printer. Choose Black and TriColor if the Photo cartridge is not being used.

Click Preview to see what you will get. Get the printer ready then click the printer icon in the preview window to print your photo.

The gThumb program interacts with the print dialog to give some additional options such as the Header and Footer. You can also print more that one photo on a sheet. When printing photos with GIMP the print dialog will not have these extras. Read the Help file for gThumb. You will find that it is both a good viewer and cataloging program, too.

On-screen vs Print Colors

Digital cameras and monitors define colors in terms of red, green and blue (RGB). Each one can vary in intensity from 0 to 255. When all three are set to zero, we get black. If all three are at the maximum 255, the result is white. With 256 shades of each color we have the possibility of 16,777,216 variations.

The RGB color model won’t work when printing colors on paper. Mixing equal amounts of red, green and blue will not yield white. And reducing the three values to zero won’t give us black. It turns out that the method of printing color on paper predates the RGB model since we had printing presses long before computers and digital cameras.

Back in the 1800’s it was discovered that cyan, magenta, yellow and black inks could be combined to produce the biggest range of colors on paper. Thus, was born the CMYK color model. The ‘K’ is for ‘Key’, known as black. It is sometimes called Process Color. Typically, in a press room one printing press applies one color as a series of tiny dots. A second press applies dots of another color, slightly offset from the first. This continues through additional presses until all four colors are applied. The result when viewed at reading distance appears in natural color.

Our inkjet and color laser printers have a big job to do when reproducing what we see on the monitor. It has to convert the RGB data into CMYK to match our inks and toners. Most of our printers do an acceptable job with no additional input. The conversion process is automatic, the manufacturer built it into the printer. Sometimes you may discover colors in a print that do not match what is visible on the monitor. That is because the range (gamut) of available colors in CMYK is not as big as in RGB. Some printers include extra ink cartridges which extend the range. Your printer may also have the option to choose a different color profile from within its firmware.

Another method of improving printed colors is by editing the image in GIMP. Along with editing, GIMP allows choosing different ICC (International Color Consortium) color profiles. The object here is to most closely match the profile of your printer. Getting a stubborn color just right can use up a bit of paper and ink before your are satisfied.