Driver09

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I don’t use Instagram, but a quick search tells me that the maximum width is 1080 pixels and the maximum height is 1350 pixels for a portrait picture or 566 pixels for a landscape one. Once you’ve resized the image appropriately, try to get the export file size below 500 KB: you’ll probably find that a JPEG quality setting of 80% or even 75% looks acceptable, but just dropping to 85% instead of 90% should give you a significant reduction in file size without noticeable loss of picture quality.

As Alfred said, there are too many pixels in your images, so you will have to scale them down. But in addition, you could use an application called imageOptim for further file size reduction. Scale down your image to the appropriate size, export from Photo at 100% JPEG quality, and apply, for instance, the Guetzli algorithm in imageOptim at a quality setting of 90%. You will be amazed …
 
https://imageoptim.com/mac
 
 
Cheers,
Alex 
 

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Deselecting parts of the image didn't work for me - I could still see a halo where the original image bled into the blurred area, regardless of the direction of the blur.  As with other blur effects, I found I got better results by cutting out the sharp area and pasting it back in when the blurring was finished.  I was able to produce a much stronger blur by reapplying the filter after I'd merged the first one.

Motion Blur is what you need for the lines on the road but the effect does not appear as strong as in Photoshop.


 
You may have to find something else to augment it.
 

Hi Driver09

Welcome to the forum

This tutorial explains how to add a motion blur effect, you can use the eraser tool to deselect certain areas of the image to preserve the car.