I am working on images in iPhone. There are lots of jpeg images which range from 35kb to 50kb. I may need to transfer this over internet which comes around 6 mb. I tried to change a 35kb jpeg image to png. The actual size got increase jpeg was 56.1kb and png is 576 kb. I used mspaint to change the format. jpeg to png should actually decrease the size of the image right ? If no is that ideal to have jpeg files on iphone or only png like typical mobile applications have ?
JPEG and PNG are very different file formats; any given image that is smaller in one may not be smaller in another. And furthermore, their quality is not directly comparable.
For example, photographic content is very well represented in JPEG. The subdivision-of-blocks composed with pattern recognition makes for a format that does a very good job of discarding visual information in a way that human eyes do not easily notice. Of course, a highly-compressed JPEG may throw away too much information and show the blocks and instantly break the illusion of photographic reality, but used carefully, JPEG is fantastic for photos of the 'real world'.
And computer-generated content is very well represented in PNG. The lossless encoding is great for showing the straight lines of standard computer-generated displays, and naively-created gradients are replicated exactly with PNG. Had JPEG been used for either straight lines or naive gradients, the shortcomings would stand out instantly. Also, because PNG can be palette-based, it can very efficiently store images with only a few dozen colors.
So, pick the file format based on its use: JPEG for photos of reality or for very good approximations of reality, and PNG for computer-generated content.
PNG files are usually smaller if their contents are graphical and contain a lot of evenly colored shapes. For photos or scans jpeg files are way smaller, since they use a much more sophisticated, yet lossy, algorithm for compression.
For your iPhone project you should use whatever is smaller, in your case jpeg.
Related
I receive jpeg compressed video frames over network in every 30 frames. But I have a low power mobile device and it seems to lag a lot if I upload with the following lines.
Texture2D tex;
tex.LoadImage(MyUDPReceiver.Instance.data_JPG);
Are there any more efficient ways to solve this problem?
You should not use JPEG or PNG images as their decoding is very slow. These textures are also decoded to uncompressed and use a lot of ram.
You should use ETC1 textures, of if you need the alpha channel, DXT5. Note that DXT5 is not supported everywhere so you might also need to support a different type of texture for this (PVRTC?).
There is tex.LoadImageRaw for this, to use it you will need to parse the header for width/height values (just a simple struct).
I have different textures for a player's helmet, shirt and pants in order to render custom uniforms. They have white space so it lays on the model correctly, but this is causing the App's file size to be huge once installed because the game has over a hundred items and each texture is 2.7 MB.
How can I tell Unity to ignore parts of the image or map the textures onto the player so that I do not need the white space? For example, cutting the whitespace out of the helmet image lowers the size to under a MB.
Thanks!
For the sake of others who read this:
The obvious answer is, cut out the empty spaces in an image editor. That will solve the problem in the way it really should be solved.
That being said, it's quite possible you are using poorly UV mapped models that need that space, and you are unable to fix this, as the person who asked this question is.
If you're in a position where it might cost a little time or money to get someone to fix it, you should, because no matter what, you're wasting space, and it will add up. No one wants a 100Mb download to get 50Mb worth of game. And if you payed someone for models and they came like this, consider taking it up with them, because this is a somewhat major flaw.
The "real" answer:
The first thing you should do is enable compression. From your picture it appears you are using the RGBA 16-bit format. This is a lower quality version of Truecolor, an uncompressed 32-bit format, but is not compressed in the "traditional" sense.
You should use the "Compressed" image import setting (To see it you must turn off Advanced settings). This will select one of several compression formats (depending on the platform), all of which are highly optimized. You can define a specific compression in the Advanced window, but it is rarely needed, as Unity is great at choosing the right one for a given situation, and can can take special cases (such as specific chipsets) into consideration.
Depending on the compression algorithm, that white space could easily end up taking next to no space, and depending on the image, the compression might end up virtually undetectable.
On average the "Compressed" setting can create several orders of magnitude of a reduction of image size.
From there, if your image is still to large you can experiment with import size. This creates a fairly linear change in space taken and quality image. You are importing at 1024x1024 right now. Importing at 512x512 will about half the amount of space taken, and half the resolution of your image, but depending on the art style, the change can often be negligible visually.
You can for more details on these changes in the documentation for the texture importer
I am trying to create a background image on a webpage, which is similar to the 404 page used on tumbler...
http://testing404image.tumblr.com/
Here we can see a PNG which is 1623*1064 pixels, yet appears reasonably smooth gradient wise.
The direct link for the image is
http://testing404image.tumblr.com/images/status_bg.png?2
When I try to create a similar PNG (different colors, but same size) in Photoshop CS4 for Mac, the resulting file ends up at > 400k, whereas tumblers is 90k
Ive tried playing with all Photoshop options, including reducing number of colors to 55, but I cannot get the image below ~240k.
Ive also tried various optimising tools such as ImageOptim (http://imageoptim.com/) but to no avail.
Are there any properties of this PNG which result in a such a low file size?
I tried using JPG, thinking its better suited to gradient images, but even a 100% quality JPG resulted in noticeable aliasing, which an identical content/size PNG didnt have.
Thanks for any advice
Hi there changed the colours with
Image > Adjustments > Hue/Saturation - In Photoshop CS4
and this is the result:
as you can see it's almost the same size (75k).
Try playing around under the
Image > Adjustments
to get the color you are looking for and save as png with NONE for interlace.
Photoshop is not very good with PNG: I simply opened and saved it with the humble xnView (maximum compression), and got 74K. You can also convert it to paletted-image, and do some extra little tuning - PNGoptim gives me a final size of 64.548. I would't expect anything much better than that, the image is just too big.
BTW, be aware that using a gradient that is so big and so smooth that it a digital image (with 8 bits per pixel) cannot represent it without some banding. That image is really oversampled (you could resample it at 25% or less and display it scaled, and the result would be basically the same)
The actual reason is the source image your looking to have a lower gradient quality than the one you are making.
Just uncheck the Dither option (from the top toolbar in Photoshop) when filling the gradient color. the quality and smoothness of the gradient is decreased and therefore you get a very smaller file sized PNG output.
I need to convert some images from pvr to a png, in run-time in iphone. I need to read them, decompress, transform some colors and then save then to pvr again or png. Any advice ?
This is apple example program that shows you how to load PVR texture files using the included PVRTexture class and then display them using OpenGL.
Do you specifically mean compressed PVRTC textures or any of the formats (e.g. 565, 1555) supported under the PVR? Also, what sort of transformations did you want to do to the colours?
The reason I ask is that, IIRC, there is code to read/manipulate PVR files on the Imagination Technologies dev web pages but if you want to change the colours of PVRTC compressed textures without actually recompressing the data entirely, there will be limits to what you can achieve. Certainly, changing the hue of regions etc will be possible, but manipulating individual pixels is likely to be too difficult.
I'm developing on the iPhone and the majority of our game is using OpenGL ES, but there are also menus that use CGImage and Quartz in order to be displayed. In OpenGL ES, I know that no matter what image compression goes in (JPG, PNG, etc.), the data stored in memory as a texture is an 8-bit texture, unless I use PVRTC in which case I can get it to 2 or 4 bits. We've been having memory issues due to large CGImages, so my question is... what sort of optimizations and compressions do Quartz and CGImage use? I can't find the details in Apple's docs, when really I want to know if it would make a difference to put a 256-color image in, or a JPG vs a PNG, if having the dimensions at a power of 2 help, etc. Speed is unimportant, memory is the bottleneck here.
Thanks.
Quartz is uncompressed. It is for quickly compositing and rendering pixel accurate content. Once your images have been drawn into a context it doesn't matter where they came from, they take whatever that context takes per pixel for however many pixels they have (generally 4 bytes per pixel in a device if I recall correctly). The one big thing it does is premultiplies the alpha to avoid blending.
Now, some views under memory pressure can evict their contents if not displayed, and reconstitute them as needed. In those cases a CGImage from a compressed source generally ends up taking less memory, but I suspect that is not relevant in the case you described.