I have a grayscale icon that I'm editing with Photoshop with a transparent background, but I can't, for the life of me, figure out how to convert the icon to one that can be used as an iPhone toolbar icon. If I simply save the image as a PNG, it doesn't show up as anti-aliased on the iPhone because every pixel with color is being rendered as black, instead of a shade of gray.
According to the Apple docs and other sources, there needs to be an alpha channel on the image to specify varying levels of transparency for each pixel. However, I have no idea what that means. I've read these posts and docs from Adobe and I still can't figure out how to properly convert a grayscale image into one that can be used as an iPhone toolbar icon. The blog post is hard to comprehend and poorly written, and the Adobe docs don't really help.
http://cahit.hayalet.net/blog/514/converting-an-image-to-iphone-toolbar-icon/
http://livedocs.adobe.com/en_US/Photoshop/10.0/help.html?content=WS74B356C9-353F-4483-8632-7B1A102F2A2E.html
Can someone point me in the right direction or provide exact, step-by-step directions to doing this in Photoshop?
It's much more simple than having to muck with actual masks in Photoshop.
iPhone toolbar icons are about 30px by 30px, so make a new Photoshop file with those dimensions. Ensure the background is transparent (you can specify that when creating a new file).
Then, any pixels you draw on top of this transparency become what iOS uses for the icon. Doesn't matter what color it is in Photoshop for NSToolbar icons -- they're automatically used as masks by iOS.
Leave transparent the parts you want to show through. Save as 24-bit PNG, and chuck into XCode as usual.
For a few icons that serve as good starting examples, check out the ones I publish for free here: http://glyphish.com Just take one of the PNGs and open it in Photoshop and you'll see that it's drawn in an arbitrary color (#444444) with varying levels of opacity to create darker and lighter parts of the icon.
This is more of a photoshop question than coding but anyway, here's a suggestion.
Lunacore has a good tutorial on how to use masks.
What you want to do is:
Make sure you're background is transparent.
Create a new layer and
fill it with any solid color.
Create a mask on the solid color
layer, and fill your greyscale image into the mask. (Use your
greyscale image as the mask.)
Toolbar icons use your image as a mask. They only consider what transparancy the image has. Not what color or shade.
Related
Sometimes pdf might have a transparent background. And In my application I have given a option to choose background. So, in case of pdf with transparent background and background color black all things becomes black black so, any way to check or any key inside dictionary of pdf page that can help me? Any help will appreciated.
The easiest solution for you would be to remove black color from available background colors.
Generally, all pdf pages have transparent background and the white background color is set by the viewer application. It is possible to set a background color for each page. You can read all about it in Page Group under Transparency section of the PDF Reference.
It is also possible to show a background color for a page by setting 'BoxColorInfo' dictionary in the page dictionary with appropriate values.
But I am not sure what you can achieve by knowing what color a page background is, since black background is going to be a problem for PDFs with transparent pages anyways.
EDIT: Following is the paragraph from PDFReference i was trying to point you to:
Ordinarily, the page is imposed directly on an output medium, such as
paper or a display screen. The page group is treated as an isolated
group, whose results are then composited with a backdrop color
appropriate for the medium. The backdrop is nominally white, although
varying according to the actual properties of the medium. However,
some applications may choose to provide a different backdrop, such as
a checkerboard or grid to aid in visualizing the effects of
transparency in the artwork.
It says that most PDFs would have a transparent and it is your application which shows the background color. Hope this helps.
I'm looking for an algorithm to overlay a color on top of existing picture. Something similar to the following app (wall painter): http://itunes.apple.com/us/app/wall-painter/id396799182?mt=8
I want a similar functionality so I can paint walls in an existing picture and change them to a different color.
I can work both in yuv or rgb mode.
To successfully paint the walls in a picture, you have to do two steps:
Find the boundary of the wall within the picture (select the part of the image to be colored)
Apply the desired color to the selected area
The first step is the hard part. It similar to what Photoshop's magic wand tool would do. And indeed a search for magic wand algorithm turns up a few good articles such as this article with Objective-C code.
The second step is much easier and can be achieve with CGContextSetBlendMode and CGContextDrawImage.
You could try drawing into a graphics context with kCGBlendModeColor. From the documentation:
Uses the luminance values of the background with the hue and saturation values of the source image. This mode preserves the gray levels in the image. You can use this mode to color monochrome images or to tint color images.
Experimenting with other blend modes might also do the trick. See the documentation for details (search for "kCGBlendMode").
The RGB and YUV color models are not really great for changing colors in this way. I think the best color model for this is HLS.
Link: RGB to HLS and HLS to RGB conversion source code
H (hue) will change the base color
L (luminance) will change the brightness
S (saturation) will change the amount of color
You can evaluate the effect of these three components in a photo editing app, like Photoshop of The GIMP.
I asked this question on the Graphic Design site, but it includes a programming component that might be better answered here.
Specifically, I have a bunch of photographic crayon images. I would like to remove the color from one to produce a neutral image that I can load into an iPhone app that I'm writing and dynamically color. The crayon images have dark regions (shadows) and light regions (shine) which I would like to preserve. I will be dynamically coloring it with many different colors, ranging from white to rainbow colors to black.
My first inclination is to turn the image into a grayscale image and then somehow turn the color channel into an alpha channel, and change the color of all pixels to black. Then I could use it as a mask. However, this would only preserve the shadows, and I would lose all the highlights.
Any ideas?
Two options come to mind:
Make a grayscale version that could be tinted as you said, with the shadows and highlights simply white and gray.
Make an outline, i.e. an image with alpha that had 0% opacity in the colored parts, say 10% white over the highlights, 10% black on the shadows, and 100% black/dark gray for the lines/edges. The idea being that you could put any color under the outline and it would look right.
First, I'm not talking about icon libraries or mockup tools/libraries.
I'm familiar with various icon libraries that people have created, but other than the stuff from the example code like UICatalog, I'm wondering if anyone knows of anyone who has created free libraries of custom button bitmaps (stretchable button images), slider handle/track bitmaps, etc Basically bitmaps to customize the look of standard controls for those controls (like buttons and sliders) that allow you to specify such bitmaps.
I'm also interested in any photoshop tutorials/templates on/for creating stretchable custom button images, bitmaps for slider parts, etc. (Afraid I'm not a huge PS god or anything.)
Anyone know of any resources like this for fancying up the standard controls?
I've been able to find several stretchable buttons by searching through my collections of sample code for: "stretchableImageWithLeftCapWidth"
From the Apple sample code, the UICatalog, BubbleLevel, iPhoneMultichannelMixerTest, avTouch, AQOffilineRenderTest, and TouchCells sample code all contain buttons with stretchable images.
Hope this helps!
Stretchable buttons is no problem - there's nothing special you need to do in Photoshop. Just make the image of the button stretchable and set the radius to that of any rounded corners you have on the button graphic.
Slider parts - I'm pretty sure you'd have to make your own UIControl from scratch.
To make a button in Photoshop, create a new file with transparent background, select the Shape tool, rectangle near the bottom of the tools, drag out a rectangle. Size doesn't matter™. For a rounded rectangle, click and hold the same tool, choose the rounded rect shape and set a corner radies (same radius as in stretchableImage later).
Double-click the layer right of the layer name to get the layer style popup. Check Color Overlay and set the color you want. Check Inner Bevel and make its size somewhere below half the height of the rectangle - I think 90 degrees for the Global Angle works well. A lower opacity and larger size makes the bevel look less chunky.
Ctrl-click (option-click) the graphics rectangle in your layer to select the button's outline. Deselect the bottom half of it by using the marquee tool (M) at the top of the tools. Select a light gray foreground color, nearly white. Create a new layer with the square icon under the layer list (Windows->Layers if not visible). Fill the selection of the new layer with the paint bucket, and drag down opacity for the layer until the 'matte laquer' effect of it looks right.
A simple button, but that's the gist of it.
I’ve been busy working on the graphics for my iPhone application. I started working on generating icons for my UITabBar and ran into lots of problems. How do you create these icons?
I created this solution:
http://www.nailrails.com/?p=46
Are there any shortcomings to this approach? It seemed to work for the few icons I created...
Apple's guidelines can be found at http://developer.apple.com/library/ios/#documentation/UserExperience/Conceptual/MobileHIG/IconsImages/IconsImages.html#//apple_ref/doc/uid/TP40006556-CH14-SW1
The docs are pretty straightforward-- alpha is all that matters when the image gets loaded by the toolbar, meaning that anything that's not at least semitransparent will render in the same opaque shade. As for how I do that, I mainly use Adobe tools. Fireworks is my preferred tool but Photoshop's also more than up to it. Another one I've had good results with is Acorn, which is frankly a lot cheaper while being more than sophisticated enough for this kind of work. I'm not really a graphic designer but a certain familiarity with this kind of stuff goes with the job.
I have an article up on my site that shows how to use OmniGraffle with a template I use to create great iPhone toolbar icons in minutes:
http://steveweller.com/articles/toolbar-icons/
The template sets up a grid to work to that corresponds to one square for each pixel. You draw your icon in white on top of the black template background and then export as a PDF exactly the right area to match the icon size you need (typically 21 pixels high). Then you reimport the PDF, resize it to the final icon size (21 pixels again), and export as PNG. The template does nothing magical; it just provides an already set up working area and helps you get the final PNG right every time to the scale is correct.
You could use the same technique in Acorn or any other app that supports PDF export and layers.
(I use Gimp. Assume your icon layer already has alpha channel.)
Right click the layer, then add layer mask.
Done with option "transfer alpha channel of layer" chosen.
Select the whole layer (but not layer mask), and clear it with pure white.
Resize image to Apple-suggested size, and export it as png file.
You may also paint directly on the layer mask.