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Hey guys, so i want to make a wallpaper for my friend and i need help setting up the document size.

I don't want to end up making such a big file that it can't be emailed to my friend. But at the same time i don't want to work on something that's too small and risk quality loss.

For example if i open up a new document and make it 2560 x 1600 pixels (my friends display size) it just seems like it would be too big to email. maybe i'm wrong though. 

 

Is this the best size? Also should i select Web document?

 

Any help is appreciated. 

 

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Set the file to 72DPI and the file size should be small enough to email if you export it to jpeg on high quality.


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 Wallpapers for Macs typically are JPEG files. Apple includes several dozen high resolution wallpaper images in the /Library/Desktop Pictures folder at the 5120 x 2880 px image size. But even though they are all the same image size, they range in file size from over 26 MB down to a bit less than 3 MB.

The reason for this difference is JPEG uses lossy compression to reduce file size at the expense of reduced image quality. In this sense 'quality' means the amount of fine detail in the image -- removing more of it results in greater compression & thus smaller file sizes. A consequence of this is that images that do not have a lot of fine detail to begin with can be compressed to smaller file sizes more than images that do, even at the same relatively high quality settings.

So, the final file size of your wallpaper exported as a JPEG will depend on how many fine details it includes, as well as the export quality setting & its pixel dimensions. If you have access to a Mac, compare for example the Zebras.jpg to the Pink Forest.jpg file in the /Library/Desktop Pictures folder -- because the first has tons of fine detail while the second has very few of them, the second can be a much smaller file without significant loss of quality. You can take advantage of this by filling areas of your wallpaper with the same color, by applying a minor amount of blurring to soften edges, etc., but that will depend on the design of your wallpaper & how you want it to look.

Also note that on Macs the System Preferences > Desktop & Screensaver offers several different ways to fill the screen with the wallpaper image, so it is not always necessary to match the screen size & image size exactly. Because of this, the DPI of the exported JPEG doesn't matter much.


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An interesting simple exercise is to create a square document 1000px x 1000px add 100px black and white stripes vertically and export that file to a jpg. Now rotate those vertical stripes so they are horizontal and export to jpg again using the same settings.

The jpg with horizontal lines will have a smaller file size than the one with vertical lines, yet they both have the same content.

 


iMac 27" Late 2015 Fully Loaded, iMac 27" Mid 2011 both running High Sierra 10.13.6 - Affinity Designer/Photo, Publisher Beta 1.7.0.140, Illustrator CC, Inkscape, Blender, Sketchup, Pepakura Designer, MTC, Pixelmator & Pixelmator Pro + more... XP-Pen Artist-22E, - iPad Pro 12.9 B|  

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30 minutes ago, firstdefence said:

The jpg with horizontal lines will have a smaller file size than the one with vertical lines, yet they both have the same content.

The same thing happens if the document is exported to PNG ... but the files are both significantly smaller than the JPEG versions, & the PNG's do not use lossy compression. They are even smaller (by about ½) if the document color space is set to 8 bit Gray instead of 8 bit RGB. :S


Affinity Photo 1.7.0 & Affinity Designer 1.7.0; macOS High Sierra 10.13.6 iMac (27-inch, Late 2012); 2.9GHz i5 CPU; NVIDIA GeForce GTX 660M; 8GB RAM
Affinity Photo 1.7.0.135 & Affinity Designer 1.7.0.9 for iPad; 6th Generation iPad 32 GB; Apple Pencil; iOS 12.3.1

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12 hours ago, R C-R said:

 Wallpapers for Macs typically are JPEG files. Apple includes several dozen high resolution wallpaper images in the /Library/Desktop Pictures folder at the 5120 x 2880 px image size. But even though they are all the same image size, they range in file size from over 26 MB down to a bit less than 3 MB.

The reason for this difference is JPEG uses lossy compression to reduce file size at the expense of reduced image quality. In this sense 'quality' means the amount of fine detail in the image -- removing more of it results in greater compression & thus smaller file sizes. A consequence of this is that images that do not have a lot of fine detail to begin with can be compressed to smaller file sizes more than images that do, even at the same relatively high quality settings.

So, the final file size of your wallpaper exported as a JPEG will depend on how many fine details it includes, as well as the export quality setting & its pixel dimensions. If you have access to a Mac, compare for example the Zebras.jpg to the Pink Forest.jpg file in the /Library/Desktop Pictures folder -- because the first has tons of fine detail while the second has very few of them, the second can be a much smaller file without significant loss of quality. You can take advantage of this by filling areas of your wallpaper with the same color, by applying a minor amount of blurring to soften edges, etc., but that will depend on the design of your wallpaper & how you want it to look.

Also note that on Macs the System Preferences > Desktop & Screensaver offers several different ways to fill the screen with the wallpaper image, so it is not always necessary to match the screen size & image size exactly. Because of this, the DPI of the exported JPEG doesn't matter much.

Thanks R C-R

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