Image looks like it has graph paper in the background

There is no separate "back light" setting like there used to be on some earlier phones.

In the Settings app of your iPhone, there is a section called "Display & Brightness". You can use that to make your phone's display brighter or dimmer, but as you have probably discovered, it dims or brightens both the foreground and the background elements together as one.

You can turn it all the way down, which is very dim and hard to see in normal indoor light conditions, but may be preferable in extreme low light conditions like in a nightclub setting, or in complete darkness.

Why isn't there a separate back light setting?
To fully answer this, I would probably have get into more than you ever wanted to know about displays.

First, there is really no background or foreground on today's smart phone displays. The foreground elements and background elements we see on the iPhone are really a graphic illusion created by lighting individual pixels with different colors. All of these pixels are on the same plane, so nothing is really behind or in front of anything else. It's just artistically drawn to look that way.

Brightness is simply an "intensity" setting applied uniformly across all of the underlying individual pixels within the display matrix, and has no relationship to color. For clarity, let's look at the difference between lightness in colors, versus display brightness:

COLOR LIGHTNESS is a matter of how much WHITE (all the RGB colors summed, for example) is present in a given color. This has nothing to do with display brightness.

DISPLAY BRIGHTNESS is a matter of how much LIGHT INTENSITY is applied uniformly across all pixels in the display matrix.

At zero display brightness, you would not see white any better than black, blue, green, red or any other color. You wouldn't see anything.

Why did you expect to be able to control the back light?

Prior to the smartphone era, the displays on early cell phones and pagers (and lots of other devices that had displays) had a lighted background that contrasted with dark foreground elements.

The background intensity was a separate setting on those devices, but that's because the background was the only thing that had intensity. The foreground elements were solid black LCD (liquid crystal display) segments that were used to form characters and very simple graphics and lines.

Everything we see on today's smartphone displays is dynamically drawn by lighting different pixels with different colors at different times. Individual pixels on a Retina display are nearly microscopic in size--they cannot be separately discerned by the eye.

Imagine a matrix of microscopic light bulbs, each of which can separately change to any of millions of colors and levels of brightness at any time, on command. Just imagine the sheer number and complexity of possible commands to control a Retina display!

Even if Apple wanted to provide a new feature that enabled us to separately control the perceived "back light", it would only be an illusion as well.

Such a feature would require some sort of complex algorithm to determine which pixels are involved in what you perceive as the "foreground" elements at any given time, so it could add intensity only to those pixels considered to be "background" at any given time.

Since "foreground" and "background" elements drastically change shape (and location) at any time, such a feature would be pretty daunting to implement.

You might be better off using a pure black graphic as your background image if your goal is to have more contrast to make the app icons stand out.

Cheers,

-=Cameron

If you want to upload your own background image or customize the sidebar and color scheme of your page, follow the steps below.

1. Sign in to your account.
2. Go to your Settings and click on the Design tab.
3. Scroll down to the Customize your own section.
4. Click on Choose file to upload a background image. images justify to the top left of the screen. You cannot stretch your image to fit. It will display as the size you uploaded (file must be smaller than 2MB).
5. Check the box to Tile background if you want your picture to repeat across the background.
6. Choose whether your Background position will be left, center or right.
7. If your image isn't very large, choose the background color that will show behind the image.
8. Choose a color for links.
9. Choose a black or white transparent overlay.
10. Click Save changes.

Source: Customizing your profile design

You can make several adjustments to improve your images such as lightening dark areas, changing the exposure, sharpening blurred edges, and changing the brightness and contrast.

• Exposure adjusts the overall intensity of light in an image.
• Adaptive Lighting improves only the dark areas in an image without affecting the bright areas.
• Brightness adjusts the amount of light in colors ranging from light to dark.
• Contrast adjusts the difference in brightness between light and dark areas of an image.
• Sharpness helps define edges and the smoothness of texture in an image. Use this tool to make a blurred image appear more focused.

Adjusting the image Follow the steps below to make adjustments:

1. Click the View tab and select the image you want to edit by either clicking the image, or by clicking the small box at the bottom left corner of the image. Figure 1: Select the image
2. Click the Edit tab and then click the Advanced tab.
3. On the Advanced tools tab, click Adjust Image .
4. Select an adjustment from the list on the left. Figure 2: Adjusting the brightness
   • The Exposure adjustment is automatically applied when the Adjust Image tool opens. Eight variations of the image are displayed on the left. The current image is displayed in the center. Each image represents a different level of adjustment. When you move the pointer over any of the images on the left, a large version of the image is displayed. Use Preferences to turn this large image preview on or off and to set the timing for the display.
   • If you want to use a different adjustment tool, select Adaptive Lighting , Brightness , Contrast , or Sharpness from the list.
5. Select one of the images on the left.
6. Do one of the following:
   • Click Accept to accept all changes and exit from the Color Toolkit.
   • Click Cancel to discard all changes and exit from the Color Toolkit.
7. If you have finished modifying the image, do one of the following to save your changes:
   • Click Save to overwrite the original image.
   • Click Save As to save the modified image with a different name.

learning to use light metering correctly can have its challenge.
the manual will guide you on how to set up to read light from the subject. spot metering a dark area will cause general overexposure, or a washed out look. spot metering a bright area will cause a dark image. if you are on spot meter and shoot two people standing together against a bright lit background, your meter will see between them if they are centered, and read all that bright background, setting the camera to a less sensitive combination of aperture / shutter speed, resulting in a dark image. use field averaging meter setting and be sure you are metering the subject and not the background. try shooting a wall that is fairly clear of other colors and uniform it light hitting it, you should have a correctly exposed image. since it works in other modes (at least 1, anyway) then it is unlikely you have an exposure compensation issue. that is the only other non defect issue that would cause your problem.
once you confirm that you have these settings correct and still get a dark image, its time to have it serviced.
good luck
mark