コマンドラインでwgetとconvertを同時に使う
$ wget -q -O - http://www.google.co.jp/intl/ja/images/google_sm.gif | convert -quality 30 -resize 200x200 - jpeg:- > a.jpg
これで良い。
$ wget -q -O - http://www.google.co.jp/intl/ja/images/google_sm.gif | convert -quality 30 -resize 200x200 - jpeg:- | ruby -e 'puts [STDIN.read].pack("m")' /9j/4AAQSkZJRgABAQEASABIAAD/2wBDABsSFBcUERsXFhceHBsgKEIrKCUl KFE6PTBCYFVlZF9VXVtqeJmBanGQc1tdhbWGkJ6jq62rZ4C8ybqmx5moq6T/ wAALCABTAMgBAREA/8QAGgABAAIDAQAAAAAAAAAAAAAAAAIFAQMEBv/EADAQ AAICAQMDAwMDAgcAAAAAAAECAAMEBRExEiFBEzJRFGFxBiKhFSMkM0JSYpGx /9oACAEBAAA/APTRERERERERERERERERIsyopZiAB5M4LNVUuUx62tI8jiRO dmDv9Mu35kV1pVbpuqKGd2Nl05K71OG25E3xERERERMHiVeoZNuOjHrJO026 RZZZjhrHLM3JMsIiImCQBueJQ5+U+bl/TVttWvu2lji4gSsADpX4E6fQTacW oaet1LdIBbxNOjYJxCSe7nky4mCQOYDA8ETMRMbj5mYiYjcSn132n8Tp0Yf4 RT9pYTHUPkQSACTwJBbq3ICuCTJKyuN1O4nNqVpqxiR5lNoK+rda7dz1T0YG wmZg94AA4E0ZmUmLUXbnwJX0i7M/uXu2x4RTsBIZWNbSDZS7jbkbyWm6qWsF N57n2tLd3CL1GcPrtkMdienxtMWJYg6l3kq8spsX9p/idj2KlfWT223lYmTd nMxRzXUDsOnkzlzrMrFG4sZkPn4mdKsOW/U9thZeV37TbrftP4nXo/bCQn4m m/MfIyTRS3Si+5hzIXYbBOqtnDfc8zRp2qOmUMa49QPYH4lt9M2y7ON1JIO3 3m2mv0lK779yZw65v9KCPmV36ccLkWVnz3E9HE1m6sHYuu/5j16uoL6i7ngb yi164tZ0b9gZb4CAUKduROh0DqQRPKalWcfIPT22bcGXVl5twlbfuUk9JUfT qfM7yARtKvNr6FceOROfIym/paDf7SX6cKvQwPKmWOfQtuM4I8Sh0MldQfb2 7bGd2ucH8TZiOa9J6h8Th0u3a+4hC7b77TvsbKyN1ZhUnwvMxjaYldgdV787 mWqjYATM586n18Z0+RPKVO+FmB9tmQ7EfInrcXIryaVsrO4P8Taw6lI+ZWZO GqI9iqdx5JlVprs+q/u7kDtNmu1Fbuo8NLXRcgXYajf9y9jLCeZ1na7PFSdz v3lga+ilRwOnabdJYKrVE9we0sZWaq4VCBy3aa68P1tP9NvjsfvK3DXL03KJ CdaHn7ywzNTNqCildns7bnxNml4AxxuO5PJ+Zq1zg/iTxUNmkdI52lTg3fTZ vU/tPZp6ita2UMuxB8zZMxMHvKrVNLXI/evZvkSppTPwLSa+4/8AZZ06vkkb PiMT9pO/Lyr6WRMcJ1DljOPS8C2nL9VzuZb52IuVT0sJSUUZmn39VJDL5B8y yOZmW17JUtZPkniasTT9rTYxLOeWMsrqA9XTKvovxrtx32nauZay/wCX3nOM d77uuzuf4lkirVX3IAHM4b8zDLFV3sb/AIDeefyi9eR6gRkAO4JEvtJ1NMlR U+y2Af8Ac06xTfbZ+wDp4m3S/XrrFThegefM5NU0tjYbaexPI+ZoxLtRxv2q N1+CZaYj5VrhshwB/tWWQ4mYmOZrehH5EiMVBxJChfMmEVeBJSDVK3ImBSg8 SYAHAmZBq1bkSIoQeJNVC8CUmtZjNYMdDsC2xnbh4ipUAoAE2X4NdqEEbzz1 lD4WqVBN/d2/E9Sqq6AkTIrVeBJFQw2Imo41ZO+0mtapwJOIiIiIiIiIiec1 vDtGQbqwSDyPibsDXFSsV5CMGHbcCdh1ihh/aV3bwAJyV41uRmHIvGzf6V+B LpB0qBJRERERERERERERIWVrYNiJytp6E7gCSTEC8bCdCVhOOZOIiIiIiIiI iIiIiIiIiIiJ/9k=