This should relate over to Paint Shop Pro (curves) and Photoshop Elements (in levels adjustment screen)

First, adjusting the mid gray point on images. This technique may sound confusing at first, but practicing this over and over again every chance you get will get it faster and faster... and once mastered you will be able to color correct almost any image given, even ones that appear to look right on screen. Using the eye sampler tool set to a 3x3 point sampler, meaning if we eye drop a piece of noise pixel it will average the pixels next to it (this tool is located under the eye dropper tool by holding it down) and the info palette, I located something that I felt should be gray. (notice the info palette, eye drop sampler tool used, marked #3 for mid-pt grays, #1 & #2 were white/black points). To obtain the white and black points, use a Threshold adjustment layer. Slide the slider to the left till only a small area is black with 5-6 pixels all bunched together, hold the shift key and run the mouse over to that area and left click. This will place a sampler point on the info palette. Do the sane, but the opposite direction...after finished, hit cancel. Click the eye drop sampler once again to show the points if they are hidden.

Now we will take these numbers and add them all and average them by dividing by 3... This average will be used in the curves adjustment as the output number for all three channels for the gray point and magic will happen.

Open curves adjustment layer, by going through the top menu or clicking the half white/half black circle at the bottom of the layers palette. Click the down arrow to get to Red. Place a new tic mark on this diagonal line about center (make sure your gradient in the left bar runs from white on top down to black, if not, click the arrows in the center of the bottom gradient). This will activate the bottom boxes, input and output. Here's where we will place the numbers, input will be the sampler number for red off the info palette... and the output would be the average number you figured. Do the same for all channels, matching the readings off the info palette for the channel and place the average for the output, the same number, for all channels. Click okay. This will take care of any color casting. I usually do a separate curves adjustment layer for white and black points.

All this sounds long and daunting... but after you do this over and over, you will get faster at it and it will give you great results every time. Now I used to eye ball the darkest points in an image, but now I rely on the threshold adjustment layer... again, click the new adjustment layer from the top menu or the half white/half black circle at bottom... choose threshold... a sort of bar graph will appear similar to a histogram... moving the slider forces everything in front of it black and behind to white.. But it's a great tool to find the whitest areas of your image and darkest... move your slider over to left until all that's black is a bunch of pixel (5-6 bunched together) hold down the shift key and place a new eye dropper sample tic mark there (if you need to zoom in, click ctrl and + at the same time, use the space bar to move around the image).. Don't click okay, instead move the slider to the right and do the same for the white area…then click cancel.

Select the eye sampler tool again to see the markings on the image (letter I)... and see the new readings on the info palette. Last Correction, another curves adjustment layer, for white and black points only. Remember how we did it for the gray. Well the white and black points already have a tic mark placed... but we will be doing the same technique as the mid-gray point.

Open Curves adjustment layer, click down arrow to Red channel. Select the white point, which will by the empty square on the top of the diagonal line. The input and output boxes become active. Place the white point sample readings for red into the input, but for the output place 240 (which will be used for the outputs on all channels). Do the same for all channels. Go back up to the red channel and click the bottom tic mark on the diagonal line, the black point. Place the reading sample for black for the red into the input box, and use 0 for all the channels outputs. (If you were printing, you should use 4 or 6 for the output, 0 for web viewing). Click okay... and check your image.

You could do a saturation boost, but most times, it's not needed unless for esthetics, I did apply one on your image through the hue/saturation adjustment layer, moving only the saturation marker.