Contrast of an image

Hi guys,
can anyone tell me what how can I learn more about the contrast of an image? What should I really do is to change the contrast of an image little by little. Can you give me a hint?
Thanks for your attention
Maddy

Look at the Java Advanced Imaging api, it supports contrast functions.
regards,
Owen

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HT2946 Why is the contrast of my images totally different when processed and then opened in CS4? Does anybody else have this issue?

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I Also have this problem!!
In my situation, the screen simply started exhibiting the same symptoms a few weeks ago (early February) for no apparent reason. At first I thought the screen was dead, but discovered the heat solution by accident. Now I turn it on and keep it from going to sleep until I go to bed. Thank goodness the battery is still awesome on this thing.
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Change contrast on an image

hi i am tryin to change the contrast of an image using lookup operation i am using a sinosuidal function for the look up table but the problem is that the original image doesnt retorn to its origin any help will be welcome
//return cambiaBrillo1(contraste, img);
byte[] lut = new byte[256];
for (int i = 0; i < 256; i++)
double scale = i + (contraste * Math.sin( (0.0245 * i) - 3.14));
if (scale > 255.0)
scale = 255.0;
else if (scale < 0.0)
scale = 0.0;
lut[i] = (byte) scale;
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ParameterBlock pb = new ParameterBlock();
pb.addSource(img);
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OK. I see the solution now. I had a theme selected to add opening titles. The border set on the pic-in-pic image looked the same colour as that theme. So I set the theme to No Theme and the image's border went away.

Exporting slide show from iPhoto to QT raises contrast and darkens images?

I have been using iPhoto to create slide shows (with transitions) which I then save as QuickTime (.mov) files. I add soundtracks to the QT.mov file in QuickTime Pro and burn the finished slide show to CD's for my friends and coworkers.
The original photographic image files come from several sources; mostly a digital camera, but often scanned color slides (from the dim, distant past). All of the images have been (painstakingly!) corrected in PhotoShop, and saved as finished size Jpeg files.
When I import the images into iPhoto, edit and arrange them in a folder and preview the show as a slideshow in iPhoto, the images still look perfect.
When I save the show by exporting it to QuickTime, all of the images get darkened and the image contrast increased.
This is making me nuts.
To quantify the unwanted "enhancement" that iPhoto seems to be applying to my images, I experimented in PhotoShop; I can make the original (correct) image match the "QT enhanced" image by decreasing the "Lightness" slider by -8 to -12, and increasing the "Contrast" slider by +11 (in whatever units PhotoShop sliders are calibrated).
The resulting change in the images is infuriating: the darkening increases the color saturation and blocks up the shadow details so that many images are unusable.. black skin tones, for example, become a dark red/brown color with an unnatural gradation from light to dark.
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iPhoto can make two different types of slide show movies. It would help to know which you're making.
One is made via the File/Export to QuickTime movie and makes a 4 track file with a simple fade effect. These use the Photo-JPEG codec.
The other is a 30 fps "video" using H.264 video codec via the "Share" menu.
A third method (rarely used) is to Export to iDVD. This makes an absurdly high data rate MPEG-4 video. This is also found under the Share menu.
The MPEG-4 video codec also includes an "automatic" gamma correction feature which compensates for the gammas difference between Mac's and PC's.
Try one export to iDVD. Include your audio track prior but use a high quality (.aiff) sound file. No need to actually "burn" the DVD. You can even close iDVD after it opens. You'll find the new movie in your Users Movie folder.
Open it with QT Pro and export to a new .mov file. Adjust the data rate to something more reasonable and add some audio compression.
If the colors still look too dark you can use the built in Filters in the Export dialog. You can adjust B&C or HSL or even use ColorSync Profiles that can help correct the image quality (if needed).

Auto contrast, Auto levels. image turns black

CS3 on macbook pro.
I know I should use other methods for levels and contrast but I have come across a strange problem. If I select auto contrast or auto levels the image turns black? Is there something that I have set in preferences incorrectly? How can I resolve this problem.
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Tony

turn off Open GL in prefs and restart Photoshop

Why exporting slide show to QuickTime raises contrast and darkens images?

I've been creating slide shows in iPhoto, then exporting them to QuickTime to create QT.mov files which contain dissolve transitions and later add soundtracks using QTPro. Lately, when I've exported the images to QuickTime, the resulting images in the QT.mov file are invariably darker and more contrasty than the originals in iPhoto; in many cases unacceptably dark.
It appears that QuickTime modifies the images when it exports them.
I've experimented in PhotoShop, and discovered that to make the original Jpeg image match the modified QT version I have to increase the "Contrast" slider +11, and decrease the "Brightness" slider about -8 to -12 (in whatever units PhotoShop sliders are calibrated in). This is an enormous amount of change to the images! Since darkening the image increases the color saturation, every image has some color shift. Black skin tones shift to a heavy red/brown, and shadow details block up unacceptably.
It seems that QuickTime is "auto correcting" the images; automatically applying the sort of tweaking that makes a lot of snapshots look "snappier".
Of course, I've already spent hours correcting my images in PhotoShop, and they're just perfect (IMHO) when I feed them into iPhoto.
iPhoto itself doesn't change anything.. the images are unmodified during the importing, editing and preview of the slideshow; it's only when it's exported to QuickTime that the images are ruined.
I'm hoping that there's some knowledgable soul out there in CyberSpace who knows a way to turn this hidden "auto-correcting" feature off.
G5 dual 2.3Ghz Mac OS X (10.4.6) Terabytes of disc space.

iPhoto can make two different types of slide show movies. It would help to know which you're making.
One is made via the File/Export to QuickTime movie and makes a 4 track file with a simple fade effect. These use the Photo-JPEG codec.
The other is a 30 fps "video" using H.264 video codec via the "Share" menu.
A third method (rarely used) is to Export to iDVD. This makes an absurdly high data rate MPEG-4 video. This is also found under the Share menu.
The MPEG-4 video codec also includes an "automatic" gamma correction feature which compensates for the gammas difference between Mac's and PC's.
Try one export to iDVD. Include your audio track prior but use a high quality (.aiff) sound file. No need to actually "burn" the DVD. You can even close iDVD after it opens. You'll find the new movie in your Users Movie folder.
Open it with QT Pro and export to a new .mov file. Adjust the data rate to something more reasonable and add some audio compression.
If the colors still look too dark you can use the built in Filters in the Export dialog. You can adjust B&C or HSL or even use ColorSync Profiles that can help correct the image quality (if needed).

How can I increase contrast of handwriting image?

I have an Acrobat XI Pro scanned pdf image of a very old handwritten letter. It is very difficult to read as scanned.

Use a photo / image editing program.
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How to alter the contrast/brightness/invert/smooth of an image? (beginner)

Hey,
I'm new to image manipulation and processing and have been told to use Java 2d with Image/ImageIO/MediaTracker/BufferedImages already in order to load and save my image, but I just can't find any nice way to learn how I would go about altering at least the brightness and contrast of the image I loaded up into the buffered image tracked by MediaTracker. After this I will be needing to invert and smooth the image then make a histogram, ais there any good tutorial or book to teach me how I woudl go about modifying the pixels within the image because so far I have no idea about what to do for the algorithm or what filter/classes/methods I should be doing from here. Can anyone help me out on how to start manipulating the images? I've seen a few random examples which don't really explain how the things work and I want to understand how to do the algorithms and processing though.

The book Filthy Rich Clients by Chet Haase and Romain Guy does a pretty good job of explaining how to work with images.
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Image contrast?

Hi,
I need to change the contrast of an image. Can anybody give sample code. Please it is very urgent..I already posted this one. But nobody responded..
Thanks for ur help,
-balaji

I'll just point you in the right direction.... no full code examples to give you.
http://java.sun.com/products/java-media/jai/
Page 1 says that it can do "simple operations like contrast" etc..

Unsigned 16-Bit Image Brightness Contrast

Hello, Everyone
I have Unsigned 16-Bit Image , I want to change the brightness & Contrast of this Image.
I dont found any VI in LabVIEW to do that with this format (there is BCG but only for 8-Bit).
I found this link for that issue:Adjusting Brightness and Contrast for 16-Bit Image
So, I used the Operators function to do that. but i dont know if the order of that functions is sensitive or NOT. see Picture
and did i realy need to use Subtract operators and Divide operators .
Best wishes
Alzhrani

Hi Al-Zahrani,
I don't believe that it matters whether you do brightness or contrast first. You can verify this by looking at a picture using both methods you showed below. However, when I did this, I did not see much of a difference and believe that you can place either brightness or contrast first. Also, you will need to include the math functions in order to perform the image processing you are trying to do. Hope this helps!
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Applications Engineer
National Instruments

Photosmart C309g-m, contrast & brightness on printed images

How does one adjust brightness and contrast on printed images?
(Std. settings produce very dark images.)
(I have, in other situations, been disatisfied with gamma adjustment compared to "canned" brightness and contrast control.)
Thanks,
Jim

Hi there jimjohnston,
Could you provide the community with a little more information to help narrow troubleshooting? What operating system are we using and what application are we printing from?
You can say thanks by clicking the Kudos Star in my post. If my post resolves your problem, please mark it as Accepted Solution so others can benefit too.

Image processing from .txt file onto an intensity graph

I am doing a mini project in my class and I was wondering if anyone could help me. It about image processing but I am bit stuck.
Heres the idea:
"An image is really nothing more than a 2D array of data. The value of every element in the array corresponds to the brightness of the image at that point.
In this project you will create a VI which loads a 2D array of data and then displays it on the screen using the Intensity Graph. Three example files (boats.txt, gordon.txt and parrot.txt) are available on the module webpage that you can use. However, you can also use any other black and white image you like, but will need to convert it to a “text image” first. To do this you can use some software called “ImageJ” which is available on the computers and is free to download.
You can vary the brightness of an image by adding the same value to every element in the array.
The contrast of an image is adjusted by multiplying every element in the array by the same value. Using numerical controls and simple array mathematics, you should adjust the brightness and contrast of your displayed image.
Some other ideas that you could try with image manipulation are:
o Invert an image (change black to white and white to black)"
First I am having problems putting my picture onto the graph. It is in the write file but the colours are not correct and the image has rotated 90 degrees. I will upload my VI so far when I get back onto my computer.
Would really appricate the help! Thank you for reading

Hi charlthedancer,
Here is an example to get you started.
Kind regards,
GajanS
Attachments:
Test.vi ‏14 KB

Performing Window Leveling operation on an Image

I need help for performing window leveling operation on an image. Which has to be triggered using Mouse Drag Event. I have been working on it for past 4days . I need help badly.
Thanks in advance
Prasad

Intensity range is defined as Window & distance between the two ends is called Window width. Intensity of the Pixels above or below the window is mapped to balck or white.I hope i was clear.
By adjusting this we can adjust the Brightness & contrast of the Image.
Prasad

Best Monitor for Image Editing?

Hi people!
Since Apple is making super-bright-extra-saturated monitors since the LED technology, I'm wondering which monitor would be good for image editing. I noticed that the LED one has too much contrast and the images looks like "already edited" in these monitors, but they're not. Is there a way to change that instead of buying a new monitor, for example? Like using a monitor calibrator, but certainly, I have found that Spyder Software to do so (or the one which comes with the Macintosh) has complicated user interface.
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Gemmac:
Welcome to the Apple Discussions. My preference has to be Adobe Photoshop Elements 4.0 (Mac). It's the little brother of the standard of the industry in image editing, Photoshop. Here's an example of some of it's advanced editing capabilities.
Do you Twango?
G5 Dual Core 2GHz, 2G RAM, 250G HD; G4 Dual 1Ghz, 1.5G RAM, 80G HD, Mac OS X (10.4.7) 22 LCD Display, 200G & 160G FW HDs, Canon S400, i850 & LIDE 50, Epson R200

Highlight/Shadow Clipping Indicator - Show the image too.

The highlight/shadow clipping indicator feature (Alt/Exposure or Alt/Blacks on my PC. Not sure what it is on a MAC)is marvellous and indispensible. But, it could be better, in my view.
When you are checking for clipping using this feature, the image disappears leaving you with only the clipped pixels. Everything else goes black.
The problem is that you only see the effect of your decision on how much clipping you want to allow (if any) when you take you finger off the Alt key.
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So, would it be possible for the highlight and shadow clipping (i.e. the blown pixels) to appear in the form of a colour on the image, *but* keeping the image visible at all times?
Thinking about it further......it would be great to be able to switch between 'blacked out' and visible in Preferences, or some such.
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D.

>Just curious though, where on the Adobe site would I have found this extremely useful piece of information?
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Video Turorial on the Adobe web site.
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Contrast of an image

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