Create jpg image with good quality


Question

I'm trying to save a jpg image but it's getting a bit blurred. I have it nicely in my image editor, but saving the image is not giving the quality I need, even with max quality defined.

If I save it as png, I get it with the sharpness I need.

Is there a way to overcome the loss of sharpness due to jpeg's compression? I really need it to be a jpg file.

You can check a sample of the image before and after here. As you can see, the orange is changing and the edges are not so sharp.

I start with a very high res jpg, change some colors, resize it, and save as jpg. If I save if first as png and then as jpg, still gets the same effect.

2012/03/30
1
0
3/30/2012 8:43:00 AM

Accepted Answer

JPEG saves brightness (luminance) and color (chrominance) of the image in separate channels.

And JPEG has an option (used in your case) to save chrominance at half of resolution, since human eye is generally much less sensitive to changes of color hue than brightness.

So what you're seeing is "4:2:2" type of JPEG. To get perfectly sharp edges you need "4:4:4" JPEG that saves chrominance at full resolution.

Some programs automatically choose "4:4:4" variant when you set quality to more than 75%, so try exporting JPEG from a different program.

OR use PNG format, which preserves hard edges and will generally work better for such image with flat areas.

2013/03/05
1
3/5/2013 9:48:00 PM

I'm not familiar with paint.net specifically, but if you see a sharp image in the editor and it's blurry after export then it is being blurred by the program, not compression. Compression doesn't create blur, but one of the ways that a program can improve the jpeg compression ratio of an image is to give it a slight blur. In Photoshop, for example, there is a blur setting for this purpose in the jpeg "Save for Web" dialog. If you look around in the paint.net export dialog, I'm guessing there will be a blur setting you overlooked earlier.

2012/03/30