Resize Photo Help

[luwenbin]

I am implementing a funcion using MagickCore to resize the photo which are uploaded by uesrs to 3 sizes, 400x600,200x300,100x150. I write the code as follow:

Code: Select all

char *blob = xxxxx //get from http request
size_t length = xxxx//get from http request
ImageInfo *blob_info = CloneImageInfo((ImageInfo *)NULL);
Image *blob_image = BlobToImage(blob_info, blob, length, exception); 
Image *resize_image1 = ResizeImage(image, 400, 600, LanczosFilter, 1.0, exception);
Image *resize_image2 = ResizeImage(image, 200, 300, LanczosFilter, 1.0, exception);
Image *resize_image3 = ResizeImage(image, 100, 150, LanczosFilter, 1.0, exception);

But according to the increase of users, the speed of resize images should be improved. I found that most of photos are jpg format, and for jpg files, it seems that we can directly convert it to N/8 sizes(N=1,2,4). The problem I met is I don't know which API I should use to directly convert to 8/N size. could anyone give me some helps? I tried the following code which can archive what I want, but I don't know whether it is correct.

Code: Select all

char *blob = xxxxx //get from http request
size_t length = xxxx//get from http request
ImageInfo *blob_info = CloneImageInfo((ImageInfo *)NULL);
Image *blob_image = BlobToImage(blob_info, blob, length, exception); 
Image *resize_image1 = ResizeImage(image, 400, 600, LanczosFilter, 1.0, exception);
size_t new_length = 0;
char *new_blob = ImageToBlob(blob_info, resize_image1, new_length, exception);
char size[10] = "200x300";
blob_info->size = malloc(strlen(size)+1);
strcpy(blob_info->size, size);
Image *resize_image2 = BlobToImage(blob_info, new_blob, new_length, exception); 
strcpy(blob_info->size, "100x150");
Image *resize_image3 = BlobToImage(blob_info, new_blob, new_length, exception); 

[magick]

Our blob is the ImageMagick logo (e.g. logo:). This code returns 640x480 as expected:

• blob_image = BlobToImage(blob_info, blob, 43693, exception);
  printf("%d %d\n",blob_image->columns,blob_image->rows);

And this code returns 160x120 as expected:

• blob_info->size = ConstantString("64x64");
  blob_image = BlobToImage(blob_info, blob, 43693, exception);
  printf("%d %d\n",blob_image->columns,blob_image->rows);

To get the exact size your are looking for you then follow with a call to ResizeImage().

We are using ImageMagick 6.5.3-0, the latest release.