KathyMorrowStudio

I'm an professional artist and I photograph subjects to paint (Wildlife, Native American, Western) I also photograph my paintings to create prints on canvas. To make prints, I'm required to send images as 300 dpi CMYK. I bought a new Canon Rebel T6i I’m learning how to use it but I’ve run into a processing problem. I’m taking images in a large file (jpeg not RAW). When if finish tweaking the image to my liking I save it in TIF or PNG format and upload the image to my printing service.

Currently on my Windows 7 computer I have Corel Paint shop Pro x. I have used it to process and am familiar with most of its features for getting the image as close to the original painting as possible. I use features such a cloning to remove my signature; perspective correction; cropping; brightness and contrast and other features.

Here is the problem with the Canon images. I load 32 GB San Disk into the computer and put the images in a file on the computer. When I hover over the images in the file, it shows they are 6 to 8 MG jpeg (about what I’d expect from my camera setting) and sufficient for my uses.

But when I open the files onto the Corel program, they are converted to 72 dpi jpeg. About 100 to 150kb I think the Corel is doing this automatically and I’ve never had that problem before with my other cameras. Does anyone know what's going on? Would you be able to recommend an image processing program that is user friendly? I'm overwhelmed with the choices on line and would appreciate some good advice. Kathy Morrow

GalaxyCat Loc: Boston, MA

I was recommended GIMP. It is free and very excellent, I was told. I am planning to download it soon. I only have a Canon EOS 620 (film) right now; I am trying to find a digital camera as soon as I can. Then I will get GIMP.

toxdoc42

I am a newbie here as well. It seems to me that 300 dpi resolution is fine for a computer monitor, but much too low for printing images! I use Photoexplosion and it allows you to lower the resolution in 2 ways, changing the dpi and changing the image size. I haven't used corel in many years, but, check to see if there is a setting that saves the files at a lower resultion or size which is changing you images as you save them.

rjaywallace Loc: Wisconsin

Have you triec contacting Corel and putting your entirely valid question to their Tech Support staff. I don’t use Corel, but based on other software I’m confident that the Corel app can be set to export the size and depth file that you prefer.

Bill_de Loc: US

Try going to

File/Preferences/File Format Preferences

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rgrenaderphoto Loc: Hollywood, CA

Paint Shop Pro isn't, professional that is. If you are a professional, use professional tools.

KathyMorrowStudio

Got File Format Preferences Looks like I may have it figured out I'm seeing the image at 6000 x 4000 pixels still showing up as 72 dpi but I can change it to 300 dpi now. GIMP looked interesting and I've downloaded it. Lots of tutorials to view it I have to start anew. I'm familiar with Corel there comfort in that :-) Thanks for all your help. Kathy

jerryc41 Loc: Catskill Mts of NY

We have several people here who use Corel, and they should be able to help you. If you don't get a response from them soon, re-post this as a "Corel Processing Problem." Your two final paragraphs should be sufficient to get the idea across.

Mary Kate Loc: NYC

OH NO!!! The spelling police are going to be all over you.

TheDman Loc: USA

DPI is completely meaningless. If the file sizes are shrinking that much then your images are being downsized, i.e., the number of pixels is being reduced.

JCam Loc: MD Eastern Shore

Not to be critical, and it is confusing, but I think PPI (Pixels per inch) and DPI are being confused & thought of as the same thing; they are not. Pixels pertain to the picture size & resolution taken by the camera, whereas DPI (dots per inch) is the density of the ink dots laid down by the printer on the paper. You didn't say what size prints you are making, but 300 DPI is more than plenty for an 11" x 14" or 12" x 18" print; anything below about 180 DPI is probably too few for most prints. For viewing on a computer screen or monitor, a resolution of 72 Pixels per inch is adequate. DPI & PPI can both be adjusted in many post processing programs.

TheDman Loc: USA

No, no, no. First of all, you point out that people are confusing ppi and dpi, then go on to do it yourself in your next sentence. And there is no ppi "adequate for viewing on a computer screen", since computer screens don't pay any attention to it!

mborn Loc: Massachusetts

Why shoot in JPEG then PP the JPEG you are losing a lot of information. shoot in RAW then save in whatever format you want better images for printing

KathyMorrowStudio

My largest prints are 12 x 24 300 dpi in cmyk is the requirement for the company I use (Catprint) The color and detail so far have matched the originals. Kathy

burkphoto Loc: High Point, NC

Here we go again... 72dpi is in the resolution header of an image because the manufacturer defaults to it. Other companies may use 180 or 240 or... ALL THIS MEANS is that a page layout program will size the available pixels at a resolution of that many dots per linear inch of the layout. The resolution header can be changed WITHOUT changing the total pixel dimensions of the image (which are really all that matter!). A 3000 by 3000 pixel image at 300dpi would make a 10" by 10" image on a printed page. The exact same file would make a 20" by 20" image at 150dpi. Pixels are numbers in files; dots are physical positions on a print or page. You can resize a pixel to make any size dot. Or you can represent a single pixel with many dots...

A 7-8 MB JPEG from your camera will expand quite a bit when saved as a TIFF! At 15:1 compression, the JPEG would be converted to a 105 to 120 MB uncompressed TIFF. So what you're describing may be perfectly normal.

However, TIFF files can be saved with many different options. You can apply LZW, or Zip, or CCITT compression to them to make them smaller. But you have to know what your printer can read. Of course, if you're doing the CMYK separation, you are also adding another channel to the equation, which adds 25% to the total file size.

I'm not familiar with Corel products. But I do know that Adobe Photoshop CC and Lightroom CC can give you full control over your images. You can open a camera original, and change the resolution header without changing pixel dimensions. Or, you can resize the image pixel dimensions AND reproduction size through interpolation. Either way, YOU have to tell the software how to do it.

Additionally, Photoshop can make CMYK separations for process color printing.

But I think what you're seeing is normal, and simply the result of decompressing the JPEG file. The actual bitmap created by the camera gets processed, and then dissected, into a compressed file. During that process, lots of information is discarded. Opening the JPEG converts (expands) what is left into (hopefully!) a decent representation of the original bitmap image. The original was HUGE. So the TIFF is huge.

For instance, my 16 megapixel camera produces images that are 4608x3456 pixels. So, doing the math of W x H x 3 color channels, we see that before the camera compresses and saves them, each image is 47.8 MB. A typical 8.5 MB JPEG of a large, fine, camera image again becomes 47.8 MB as an uncompressed RGB TIFF. If the camera had more megapixels to start with, the JPEG might be more heavily compressed to get roughly the same size JPEG file.