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Generate high resolution images


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Hi Ivan. If you hover your mouse over the option, there is a tooltip there:

 

This will generate an additional file for each image (thus doubling your total amount of image files). Resolution of these images will be twice higher.

 

If you combine it with the normal "help text" under the option:

 

Enable to optimize the display of your images on high pixel density screens.

 

...it is probably a feature for website visitors with Retina/High-res smartphones and tablets. Same as what they also did with the similar logo option recently...

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Yes but if I have uploaded images of 800x800px and that is also the dimension of the images on the site I should have uploaded 1600x1600px to get a good high-res images.

 

So if I enable that option I get my 800x800px scaled to 1600x1600px but it will look bad, right?

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As I understand it, it all comes down to the pixel ratio of a screen and the sharpness of the image. If a screen has a pixel ratio of 2, that means it packs 4 bitmap pixels (2 x 2) in one pixel.

So if you have a sharp image at 800x800px that you stretch to a fuzzy 1600x1600px, on a retina display the 1600x1600px image will look as sharp as the 800x800px looks on a non-retina display. I think the main objective is to not observe any difference in image quality when switching from a device to another.

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  • 4 months later...

Hi,

 

This thread is the closest I have found to answering my question about hi dpi screens and prestashop, yet it doesn't quite get there.

 

I would also like to know if I should be uploading image at 2x 800px x 800px for use with this feature (i.e. 1600px x 1600px). It is my understanding from hi dpi (retina) devices that a 2x resolution image is used for the hi dpi screen (eg 1600x1600) and a 1x image is used for regular screens (i.e. 800x800). It would make sense to me that we upload the high res image and allow Prestahop to create the 1x image from that. I cannot see how Prestahop can create a higher pixel dense image fro a 800x800 image when the information isnt there to begin with.

 

So the question remains, for product images that are set to 800x800 in the image preferences, and the 'Generate high resolution images' setting set to YES, what size images is recommended 800x800 or 1600x1600.

 

Thanks

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Ideally your original image that you upload will have at least the high DPI resolution that you want (1600px x 1600px).

Otherwise if you only have 800px x 800px, PrestaShop will just double the information available in order to make it twice as big.

This should do the job and you shouldn't notice any significant difference in image quality on a high DPI display, at least not until you zoom in. 

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