Rebel SL1 - How to upload square image 30x30 (300dpi)

[artistpam]

HI All,

Pam here, new to all of this. The site Apealz that sells digital skins wants my work. I want to sell to the but I can't seem to get the resolution high for them to upload? They want  a sq image with 300 dpi? What the hell? I have a Cannon Rebel SL1. I've shot and printed 30 x 40 image but I can't satisfy this company?? Any suggestions? And they want Jpeg not RAW . Thanks in advance, Pam

[Stephen]

You can do this in Preview. Long click your image from Photos, then go to Edit With -> Preview. Then go to Tools -> Adjust Size:

[Anonymous]

But 30 inches x 30 inches at 300 dots per inch?

[johnrmoyer]

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@artistpam wrote:

I work on MAC-UGH!!

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I use the free to download Canon DPP on my iMac. When saving, one may specify dots per inch and the size in inches.

The Apple photos,app included with macOS also works well and knows how to edit raw photos from Canon cameras.

[artistpam]

So my hubby says you can lower res but not increase. I'm in Light Room and can't resize my images? Hmmm...

[johnrmoyer]

GraphicsMagick and Gimp have good algorithms for upsizing an image.

A good explanation for what to expect is at: https://www.cambridgeincolour.com/tutorials/image-interpolation.htm

https://www.cambridgeincolour.com/tutorials/image-resize-for-web.htm

https://www.cambridgeincolour.com/tutorials/digital-photo-enlargement.htm

https://www.cambridgeincolour.com/tutorials/digital-panoramas.htm

[Waddizzle]

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@Anonymous wrote:

But 30 inches x 30 inches at 300 dots per inch?

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Upscaling the number of pixels isn’t a major problem.  It has very little to no impact on the sharpness of an image.  For example, (1) pixel can be easily converted into (4) of them in a 2x2 array with each pixel having the same color as the original.  

Doing so with a 3x3 array for each pixel would triple the image size, say 3000 x 3000 to 9000 x 9000.

[artistpam]

Thank you. I'll check it out. The company won't accept  RAW, JPEG only. Ugh I thought having my work accepted would be the hurdle... Thanks again! Pam

[johnrmoyer]

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@artistpam wrote:

Thank you. I'll check it out. The company won't accept  RAW, JPEG only. Ugh I thought having my work accepted would be the hurdle... Thanks again! Pam

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I suggest using either Canon DPP or Apple photos.app to create the JPEG from the RAW produced by the camera. If there is no upload size limit for the JPEG file, then I suggest setting the JPEG quality to "10" in Canon DPP. Using natural light on a cloudy day and setting the white balance from a white sheet of paper which is later cropped out of the image is one low cost way to get the colors close to right.

Editing the RAW in Canon DPP has the advantage of Digital Lens Optimizer if you are using a Canon lens. I zoom to 400% in DPP when choosing the amount for Digital Lens Optimizer.

Apple photos.app has the advantage of being able to do some things automatically.

[artistpam]

HI. It's the ratio aspect that's the kicker-4000 x 4000-a sq image? The company is Apealz-they want my art to make digital skins, why is this so difficult? 

[Waddizzle]

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@artistpam wrote:

HI. It's the ratio aspect that's the kicker-4000 x 4000-a sq image? The company is Apealz-they want my art to make digital skins, why is this so difficult? 

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I’ve never used Canon DPP4 on a Mac, even though I own one.  I really do not use it for photo processing.  I began using LR on a Windows PC and still do.

I believe Canon DPP4 has the “Batch” processor that allows you to specify pixel density, DPI, and final image size in pixels or in/mm.  

You should only need to crop your image to the correct ratio, which sounds like a square 1:1 ratio.