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Ogunnowo857

: Background images get distorted or random lines appear The question might not seem to be clear but i could not get a better name for the behavior of the background that happens. There is a

@Ogunnowo857

Posted in: #AdobePhotoshop #Blur #ImageQuality

The question might not seem to be clear but i could not get a better name for the behavior of the background that happens. There is a background image that i am setting to my layout, there are various resolutions of the same background put in the appropriate drawable folders also. But when the same image is seen on an emulator there are no issues, though when the application is deployed on a device, the background appears as under:



The image seems to have abnormal lines here and there. It happens for every image that is already in the form of gaussian blur or even those that i would blurred my self.

The same has been tested on different devices with better resolutions (The images are quite large too), but the same effect is seen. Can something be done to the images or is there any way this can be prevented ?

Question: I am messing up with the image when i apply the gaussian blur. I have feelings that some information gets lost when i try to save the image :(.

P.S: I have googled for a solution to this, but i could not get the correct terms may be to arrive at a solution. I have also used an image with a huge resolution say 2100 * 1024 and if i dont blur it using photoshop the image appears well, but if i apply the gaussian blur filter the same happens like the image below.

Software: Photoshop cs4 currently.

I have posted this on StackOverflow but since i do not really know to which site it belongs to, i am posting it here too. If it is not relevant for this section, you could get back and i will close it :)

Thanks.

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@Tiffany317

What I see in the image, which I think is what you're asking about, is some posterization. Whenever you deploy very smooth gradients you can run into this issue if the display doesn't have the bit-depth or color gamut to render the gradients smoothly. Ironically, perhaps, blur not only doesn't help, it can make the situation worse.

Working in Photoshop on a good quality monitor the problem doesn't show up, but when it gets onto a lower class of display you have an issue.

The remedy is to add some noise in the original. This dithers the colors and removes those hard edges. About 2-4% is usually enough, but you may have to experiment a bit. Filter > Noise > Add Noise is your starting point. Gaussian noise may work better at low percentages. Leave the Monochrome checkbox blank.

One more point: don't save the image in an indexed color format like 8-bit png or as a gif. That will cause banding such as you're seeing, even with dither. Jpeg is what you need here, to conserve both appearance and bandwidth.

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